diff --git a/basex-api/src/main/java/org/basex/http/web/WebModule.java b/basex-api/src/main/java/org/basex/http/web/WebModule.java
index a6e52ea468..af5bd95bda 100644
--- a/basex-api/src/main/java/org/basex/http/web/WebModule.java
+++ b/basex-api/src/main/java/org/basex/http/web/WebModule.java
@@ -58,7 +58,7 @@ void parse(final Context ctx) throws QueryException, IOException {
     try(QueryContext qc = qc(ctx)) {
       // loop through all functions
       final String name = file.name();
-      for(final StaticFunc sf : qc.functions.funcs()) {
+      for(final StaticFunc sf : qc.functions) {
         // only add functions that are defined in the same module (file)
         if(sf.expr != null && name.equals(new IOFile(sf.info.path()).name())) {
           final RestXqFunction rxf = new RestXqFunction(sf, this, qc);
diff --git a/basex-core/src/main/java/org/basex/query/QueryContext.java b/basex-core/src/main/java/org/basex/query/QueryContext.java
index 44325d2de3..661c571f36 100644
--- a/basex-core/src/main/java/org/basex/query/QueryContext.java
+++ b/basex-core/src/main/java/org/basex/query/QueryContext.java
@@ -259,14 +259,14 @@ public LibraryModule parseLibrary(final String query, final String uri) throws Q
    * @throws QueryException query exception
    */
   public void assign(final StaticFunc func, final Expr... args) throws QueryException {
-    for(final StaticFunc sf : functions.funcs()) {
+    for(final StaticFunc sf : functions) {
       if(func.info.equals(sf.info)) {
         // disable inlining of called function to ensure explicit locks are considered
         if(!sf.anns.contains(Annotation._BASEX_INLINE)) {
           sf.anns = sf.anns.attach(new Ann(sf.info, Annotation._BASEX_INLINE, Itr.ZERO));
         }
         // create and assign function call
-        final StaticFuncCall call = new StaticFuncCall(sf.name, args, null, sf.info, true);
+        final StaticFuncCall call = new StaticFuncCall(sf.name, args, null, sf.info);
         call.setFunc(sf);
         main = new MainModule(call, new VarScope(), sf.sc);
         updating = sf.updating();
diff --git a/basex-core/src/main/java/org/basex/query/QueryParser.java b/basex-core/src/main/java/org/basex/query/QueryParser.java
index 504a0a3ebf..67661da154 100644
--- a/basex-core/src/main/java/org/basex/query/QueryParser.java
+++ b/basex-core/src/main/java/org/basex/query/QueryParser.java
@@ -68,8 +68,6 @@ public class QueryParser extends InputParser {
       SCHEMA_ELEMENT, PROCESSING_INSTRUCTION, TEXT, ARRAY, ENUM, FN, FUNCTION, GET, IF,
       ITEM, MAP, RECORD, SWITCH, TYPE, TYPESWITCH);
 
-  /** URIs of modules loaded by the current file. */
-  public final TokenSet moduleURIs = new TokenSet();
   /** Query context. */
   public final QueryContext qc;
   /** Static context. */
@@ -84,8 +82,6 @@ public class QueryParser extends InputParser {
   private final ArrayList<StaticVar> vars = new ArrayList<>();
   /** Parsed functions. */
   private final ArrayList<StaticFunc> funcs = new ArrayList<>();
-  /** Function references. */
-  private final ArrayList<FuncRef> funcRefs = new ArrayList<>();
   /** Types. */
   private final QNmMap<SeqType> declaredTypes = new QNmMap<>();
   /** Public types. */
@@ -161,7 +157,7 @@ final MainModule parseMain() throws QueryException {
 
       final VarScope vs = localVars.popContext();
       final MainModule mm = new MainModule(expr, vs, sc);
-      mm.set(funcs, vars, publicTypes, moduleURIs, namespaces, options, moduleDoc);
+      mm.set(funcs, vars, publicTypes, sc.imports, namespaces, options, moduleDoc);
       finish(mm);
       check(mm);
       return mm;
@@ -211,7 +207,7 @@ final LibraryModule parseLibrary(final boolean root) throws QueryException {
 
       qc.modStack.pop();
       final LibraryModule lm = new LibraryModule(sc);
-      lm.set(funcs, vars, publicTypes, moduleURIs, namespaces, options, moduleDoc);
+      lm.set(funcs, vars, publicTypes, sc.imports, namespaces, options, moduleDoc);
       return lm;
     } catch(final QueryException expr) {
       mark();
@@ -271,13 +267,6 @@ private void finish(final MainModule mm) throws QueryException {
     qnames.assignURI(this, 0);
     if(sc.elemNS != null) sc.ns.add(EMPTY, sc.elemNS, null);
     RecordType.resolveRefs(recordTypeRefs, namedRecordTypes);
-
-    for(final FuncRef fr : funcRefs) fr.resolve();
-
-    if(qc.contextValue != null) {
-      final Expr ctx = qc.contextValue.expr;
-      if(!sc.mixUpdates && ctx.has(Flag.UPD)) throw error(UPCTX, ctx);
-    }
   }
 
   /**
@@ -288,15 +277,21 @@ private void finish(final MainModule mm) throws QueryException {
   private void check(final MainModule main) throws QueryException {
     // add record constructor functions for built-in record types
     for(final RecordType rt : Records.BUILT_IN.values()) {
-      if(qc.functions.get(rt.name(), rt.minFields()) == null) {
+      if(qc.functions.get(sc, rt.name(), rt.minFields()) == null) {
         declareRecordConstructor(rt, info());
       }
     }
 
-    // check function calls and variable references
-    qc.functions.check(qc);
+    // resolve function calls
+    qc.functions.resolve();
+    // check variable references
     qc.vars.check();
 
+    if(qc.contextValue != null) {
+      final Expr ctx = qc.contextValue.expr;
+      if(!sc.mixUpdates && ctx.has(Flag.UPD)) throw error(UPCTX, ctx);
+    }
+
     if(qc.updating) {
       // check updating semantics if updating expressions exist
       if(!sc.mixUpdates) {
@@ -738,8 +733,8 @@ private void moduleImport() throws QueryException {
     final byte[] uri = trim(stringLiteral());
     if(uri.length == 0) throw error(NSMODURI);
     if(!Uri.get(uri).isValid()) throw error(INVURI_X, uri);
-    if(moduleURIs.contains(token(uri))) throw error(DUPLMODULE_X, uri);
-    moduleURIs.add(uri);
+    if(sc.imports.contains(token(uri))) throw error(DUPLMODULE_X, uri);
+    sc.imports.add(uri);
 
     // add non-default namespace
     if(prefix != EMPTY) {
@@ -943,7 +938,9 @@ private void functionDecl(final AnnList anns) throws QueryException {
     if(reserved(name)) throw error(RESERVED_X, name.local());
 
     wsCheck("(");
-    if(sc.module != null && !eq(name.uri(), sc.module.uri())) throw error(MODULENS_X, name);
+    if(!anns.contains(Annotation.PRIVATE)) {
+      if(sc.module != null && !eq(name.uri(), sc.module.uri())) throw error(MODULENS_X, name);
+    }
 
     localVars.pushContext(false);
     final Params params = paramList(true);
@@ -953,7 +950,7 @@ private void functionDecl(final AnnList anns) throws QueryException {
     final byte[] uri = name.uri();
     if(NSGlobal.reserved(uri) || Functions.builtIn(name) != null)
       throw FNRESERVED_X.get(ii, name.string());
-    final StaticFunc func = qc.functions.declare(name, params, expr, anns, doc, vs, ii);
+    final StaticFunc func = qc.functions.declare(sc, name, params, expr, anns, doc, vs, ii);
     funcs.add(func);
   }
 
@@ -1079,7 +1076,8 @@ private void declareRecordConstructor(final RecordType rt, final InputInfo ii)
     final Expr expr = new CRecord(ii, rt, args);
     final String doc = docBuilder.toString();
     final VarScope vs = localVars.popContext();
-    final StaticFunc func = qc.functions.declare(name, params, expr, rt.anns(), doc, vs, info());
+    final StaticFunc func = qc.functions.declare(sc, name, params, expr, rt.anns(), doc, vs,
+        info());
     funcs.add(func);
   }
 
@@ -2069,10 +2067,7 @@ private Expr arrow() throws QueryException {
           expr = Functions.dynamic(ex, fb);
         } else  {
           final QNm funcName = name;
-          final boolean hasImport = moduleURIs.contains(funcName.uri());
-          final FuncRef ref = new FuncRef(() -> Functions.get(funcName, fb, qc, hasImport));
-          funcRefs.add(ref);
-          expr = ref;
+          expr = qc.functions.newRef(() -> Functions.get(funcName, fb, qc));
         }
         if(mapping) {
           expr = new GFLWOR(ii, fr, expr);
@@ -2747,10 +2742,7 @@ private Expr functionItem() throws QueryException {
         if(num instanceof final Itr itr) {
           final int i = (int) itr.itr();
           final InputInfo info = info();
-          final boolean hasImport = moduleURIs.contains(name.uri());
-          final FuncRef fr = new FuncRef(() -> Functions.item(name, i, false, info, qc, hasImport));
-          funcRefs.add(fr);
-          return fr;
+          return qc.functions.newRef(() -> Functions.item(name, i, false, info, qc));
         }
       }
     }
@@ -2975,10 +2967,7 @@ private Expr functionCall() throws QueryException {
       skipWs();
       if(current('(')) {
         final FuncBuilder fb = argumentList(true, null);
-        final boolean hasImport = moduleURIs.contains(name.uri());
-        final FuncRef fr = new FuncRef(() -> Functions.get(name, fb, qc, hasImport));
-        funcRefs.add(fr);
-        return fr;
+        return qc.functions.newRef(() -> Functions.get(name, fb, qc));
       }
     }
     pos = p;
diff --git a/basex-core/src/main/java/org/basex/query/StaticContext.java b/basex-core/src/main/java/org/basex/query/StaticContext.java
index 07ff6a03fc..9a6d95a532 100644
--- a/basex-core/src/main/java/org/basex/query/StaticContext.java
+++ b/basex-core/src/main/java/org/basex/query/StaticContext.java
@@ -42,6 +42,8 @@ public final class StaticContext {
   public byte[] funcNS;
   /** Name of module (not assigned for main module). */
   public QNm module;
+  /** URIs of modules loaded by the current file. */
+  public final TokenSet imports = new TokenSet();
 
   /** Construction mode. */
   public boolean strip;
diff --git a/basex-core/src/main/java/org/basex/query/func/FuncRef.java b/basex-core/src/main/java/org/basex/query/func/FuncRef.java
deleted file mode 100644
index 0f4ca3d5b2..0000000000
--- a/basex-core/src/main/java/org/basex/query/func/FuncRef.java
+++ /dev/null
@@ -1,62 +0,0 @@
-package org.basex.query.func;
-
-import org.basex.query.*;
-import org.basex.query.expr.*;
-import org.basex.query.value.type.*;
-import org.basex.query.var.*;
-import org.basex.util.*;
-import org.basex.util.hash.*;
-
-/**
- * A reference to an unresolved function call or named function item, to be resolved after parsing,
- * when all user-defined function declarations have been processed.
- *
- * @author BaseX Team, BSD License
- * @author Gunther Rademacher
- */
-public final class FuncRef extends Single {
-  /** Function to resolve this reference. */
-  private final QuerySupplier<Expr> resolve;
-
-  /**
-   * Constructor.
-   * @param resolve function to resolve the reference
-   */
-  public FuncRef(final QuerySupplier<Expr> resolve) {
-    super(null, null, Types.ITEM_ZM);
-    this.resolve = resolve;
-  }
-
-  /**
-   * Resolves the function reference.
-   * @throws QueryException query exception
-   */
-  public void resolve() throws QueryException {
-    expr = resolve.get();
-  }
-
-  @Override
-  public void checkUp() throws QueryException {
-    expr.checkUp();
-  }
-
-  @Override
-  public boolean vacuous() {
-    return expr.vacuous();
-  }
-
-  @Override
-  public Expr compile(final CompileContext cc) throws QueryException {
-    return expr.compile(cc);
-  }
-
-  @Override
-  public Expr copy(final CompileContext cc, final IntObjectMap<Var> vm) {
-    throw Util.notExpected();
-  }
-
-  @Override
-  public void toString(final QueryString qs) {
-    expr.toString(qs);
-  }
-}
diff --git a/basex-core/src/main/java/org/basex/query/func/Functions.java b/basex-core/src/main/java/org/basex/query/func/Functions.java
index a01d3edf67..828078adb8 100644
--- a/basex-core/src/main/java/org/basex/query/func/Functions.java
+++ b/basex-core/src/main/java/org/basex/query/func/Functions.java
@@ -77,15 +77,14 @@ public static boolean staticURI(final byte[] uri) {
    * @param qnm function name
    * @param fb function arguments
    * @param qc query context
-   * @param hasImport indicates whether a module import for the function name's URI was present
    * @return function call
    * @throws QueryException query exception
    */
-  public static Expr get(final QNm qnm, final FuncBuilder fb, final QueryContext qc,
-      final boolean hasImport) throws QueryException {
+  public static Expr get(final QNm qnm, final FuncBuilder fb, final QueryContext qc)
+      throws QueryException {
 
     // partial function call?
-    if(fb.placeholders > 0) return dynamic(item(qnm, fb.arity, false, fb.info, qc, hasImport), fb);
+    if(fb.placeholders > 0) return dynamic(item(qnm, fb.arity, false, fb.info, qc), fb);
 
     final QNm name = funcName(qnm, fb.arity, fb.info, qc);
 
@@ -103,7 +102,7 @@ public static Expr get(final QNm qnm, final FuncBuilder fb, final QueryContext q
     }
 
     // user-defined function
-    return staticCall(name, fb, qc, hasImport);
+    return staticCall(name, fb, qc);
   }
 
   /**
@@ -144,12 +143,11 @@ public static Expr dynamic(final Expr expr, final FuncBuilder fb) throws QueryEx
    * @param runtime {@code true} if this method is called at runtime
    * @param info input info (can be {@code null})
    * @param qc query context
-   * @param hasImport indicates whether a module import for the function name's URI was present
    * @return literal if found, {@code null} otherwise
    * @throws QueryException query exception
    */
   public static Expr item(final QNm qnm, final int arity, final boolean runtime,
-      final InputInfo info, final QueryContext qc, final boolean hasImport) throws QueryException {
+      final InputInfo info, final QueryContext qc) throws QueryException {
 
     final FuncBuilder fb = new FuncBuilder(info, arity, runtime);
     final QNm name = funcName(qnm, arity, info, qc);
@@ -181,9 +179,9 @@ public static Expr item(final QNm qnm, final int arity, final boolean runtime,
     }
 
     // user-defined function
-    final StaticFunc sf = qc.functions.get(name, arity);
+    final StaticFunc sf = qc.functions.get(info.sc(), name, arity);
     if(sf != null) {
-      final Expr func = item(sf, fb, qc, hasImport);
+      final Expr func = item(sf, fb, qc);
       if(sf.updating) qc.updating();
       return func;
     }
@@ -200,12 +198,7 @@ public static Expr item(final QNm qnm, final int arity, final boolean runtime,
     }
     if(runtime) return null;
 
-    // closure
-    final StaticFuncCall call = staticCall(name, fb, qc, hasImport);
-    // safe cast (no context dependency, no runtime evaluation)
-    final Closure closure = (Closure) item(call, fb, null, name, false, false);
-    qc.functions.register(closure);
-    return closure;
+    throw qc.functions.unknownFunctionError(name, arity, info);
   }
 
   /**
@@ -214,16 +207,16 @@ public static Expr item(final QNm qnm, final int arity, final boolean runtime,
    * with no namespace.
    * @param name function name
    * @param arity number of arguments
-   * @param info input info (can be {@code null})
+   * @param info input info
    * @param qc query context
    * @return function name
    */
   private static QNm funcName(final QNm name, final int arity, final InputInfo info,
       final QueryContext qc) {
 
-    if(name.hasURI() || qc.functions.get(name, arity) != null) return name;
-    final StaticContext sc = info != null ? info.sc() : null;
-    return new QNm(name.local(), sc != null && sc.funcNS != null ? sc.funcNS : FN_URI);
+    final StaticContext sc = info.sc();
+    if(name.hasURI() || qc.functions.get(sc, name, arity) != null) return name;
+    return new QNm(name.local(), sc.funcNS != null ? sc.funcNS : FN_URI);
   }
 
   /**
@@ -322,20 +315,18 @@ private static Cast constructorCall(final QNm name, final FuncBuilder fb) throws
    * @param name function name
    * @param fb function arguments
    * @param qc query context
-   * @param hasImport indicates whether a module import for the function name's URI was present
    * @return function call
    * @throws QueryException query exception
    */
   private static StaticFuncCall staticCall(final QNm name, final FuncBuilder fb,
-      final QueryContext qc, final boolean hasImport) throws QueryException {
+      final QueryContext qc) throws QueryException {
 
     if(NSGlobal.reserved(name.uri()) && !Records.BUILT_IN.contains(name)) {
       throw qc.functions.similarError(name, fb.info);
     }
 
-    final StaticFuncCall call = new StaticFuncCall(name, fb.args(), fb.keywords, fb.info,
-        hasImport);
-    qc.functions.register(call);
+    final StaticFuncCall call = new StaticFuncCall(name, fb.args(), fb.keywords, fb.info);
+    qc.functions.setFunc(call, qc);
     return call;
   }
 
@@ -344,19 +335,18 @@ private static StaticFuncCall staticCall(final QNm name, final FuncBuilder fb,
    * @param sf static function
    * @param fb function arguments
    * @param qc query context
-   * @param hasImport indicates whether a module import for the function name's URI was present
    * @return function item
    * @throws QueryException query exception
    */
-  public static Expr item(final StaticFunc sf, final FuncBuilder fb, final QueryContext qc,
-      final boolean hasImport) throws QueryException {
+  public static Expr item(final StaticFunc sf, final FuncBuilder fb, final QueryContext qc)
+      throws QueryException {
 
     final FuncType sft = sf.funcType();
     final int arity = fb.params.length;
     for(int a = 0; a < arity; a++) fb.add(sf.paramName(a), sft.argTypes[a], qc);
     final FuncType ft = FuncType.get(fb.anns, sft.declType, Arrays.copyOf(sft.argTypes, arity));
 
-    final StaticFuncCall call = staticCall(sf.name, fb, qc, hasImport);
+    final StaticFuncCall call = staticCall(sf.name, fb, qc);
     if(call.func != null) fb.anns = call.func.anns;
     return item(call, fb, ft, sf.name, sf.updating, false);
   }
diff --git a/basex-core/src/main/java/org/basex/query/func/StaticFuncCall.java b/basex-core/src/main/java/org/basex/query/func/StaticFuncCall.java
index 0c93d3b1a7..61bd9c4633 100644
--- a/basex-core/src/main/java/org/basex/query/func/StaticFuncCall.java
+++ b/basex-core/src/main/java/org/basex/query/func/StaticFuncCall.java
@@ -34,8 +34,6 @@ public final class StaticFuncCall extends FuncCall {
   QNmMap<Expr> keywords;
   /** Placeholder for an external call (if not {@code null}, will be returned by the compiler). */
   ParseExpr external;
-  /** Indicates whether a module import for the function name's URI was present. */
-  final boolean hasImport;
 
   /**
    * Function call constructor.
@@ -43,11 +41,10 @@ public final class StaticFuncCall extends FuncCall {
    * @param args positional arguments
    * @param keywords keyword arguments (can be {@code null})
    * @param info input info (can be {@code null})
-   * @param hasImport indicates whether a module import for the function name's URI was present
    */
   public StaticFuncCall(final QNm name, final Expr[] args, final QNmMap<Expr> keywords,
-      final InputInfo info, final boolean hasImport) {
-    this(name, args, (StaticFunc) null, info, hasImport);
+      final InputInfo info) {
+    this(name, args, (StaticFunc) null, info);
     this.keywords = keywords;
   }
 
@@ -57,14 +54,12 @@ public StaticFuncCall(final QNm name, final Expr[] args, final QNmMap<Expr> keyw
    * @param args arguments
    * @param func referenced function (can be {@code null})
    * @param info input info (can be {@code null})
-   * @param hasImport indicates whether a module import for the function name's URI was present
    */
   private StaticFuncCall(final QNm name, final Expr[] args, final StaticFunc func,
-      final InputInfo info, final boolean hasImport) {
+      final InputInfo info) {
     super(info, args);
     this.name = name;
     this.func = func;
-    this.hasImport = hasImport;
   }
 
   @Override
@@ -127,7 +122,7 @@ public Value value(final QueryContext qc) throws QueryException {
 
   @Override
   public StaticFuncCall copy(final CompileContext cc, final IntObjectMap<Var> vm) {
-    return copyType(new StaticFuncCall(name, Arr.copyAll(cc, vm, exprs), func, info, hasImport));
+    return copyType(new StaticFuncCall(name, Arr.copyAll(cc, vm, exprs), func, info));
   }
 
   /**
@@ -156,8 +151,10 @@ public void setFunc(final StaticFunc sf) throws QueryException {
       }
     }
     // check visibility
-    if(sf.anns.contains(Annotation.PRIVATE) && !sf.sc.baseURI().eq(sc().baseURI()))
+    if(sf.anns.contains(Annotation.PRIVATE)
+        && !Token.eq(QNm.uri(sf.sc.module), QNm.uri(sc().module))) {
       throw FUNCPRIVATE_X.get(info, name.string());
+    }
   }
 
   /**
diff --git a/basex-core/src/main/java/org/basex/query/func/StaticFuncs.java b/basex-core/src/main/java/org/basex/query/func/StaticFuncs.java
index 0a70f4f799..87941e0748 100644
--- a/basex-core/src/main/java/org/basex/query/func/StaticFuncs.java
+++ b/basex-core/src/main/java/org/basex/query/func/StaticFuncs.java
@@ -1,13 +1,16 @@
 package org.basex.query.func;
 
 import static org.basex.query.QueryError.*;
+import static org.basex.query.QueryText.*;
 
 import java.util.*;
 
 import org.basex.core.*;
 import org.basex.query.*;
+import org.basex.query.ann.*;
 import org.basex.query.expr.*;
 import org.basex.query.func.java.*;
+import org.basex.query.util.hash.*;
 import org.basex.query.util.list.*;
 import org.basex.query.util.parse.*;
 import org.basex.query.value.item.*;
@@ -24,14 +27,18 @@
  * @author BaseX Team, BSD License
  * @author Christian Gruen
  */
-public final class StaticFuncs extends ExprInfo {
-  /** Function caches. */
-  private final TokenObjectMap<FuncCache> caches = new TokenObjectMap<>();
-  /** Function calls. */
-  private Map<StaticFunc, ArrayList<StaticFuncCall>> callsMap;
+public final class StaticFuncs extends ExprInfo implements Iterable<StaticFunc> {
+  /** Functions grouped by declaring module, then by QName, with lists of overloads. */
+  private final TokenObjectMap<QNmMap<ArrayList<StaticFunc>>> funcsByModule =
+      new TokenObjectMap<>();
+  /** Unresolved function references. */
+  private final ArrayList<FuncRef> unresolvedRefs = new ArrayList<>();
+  /** Function calls by function. */
+  private final Map<StaticFunc, ArrayList<StaticFuncCall>> callsMap = new IdentityHashMap<>();
 
   /**
    * Declares a new user-defined function.
+   * @param sc static context
    * @param name function name
    * @param params parameters with variables and optional default values
    * @param expr function body (can be {@code null})
@@ -42,39 +49,61 @@ public final class StaticFuncs extends ExprInfo {
    * @return static function reference
    * @throws QueryException query exception
    */
-  public StaticFunc declare(final QNm name, final Params params, final Expr expr,
-      final AnnList anns, final String doc, final VarScope vs, final InputInfo info)
-      throws QueryException {
+  public StaticFunc declare(final StaticContext sc, final QNm name, final Params params,
+      final Expr expr, final AnnList anns, final String doc, final VarScope vs,
+      final InputInfo info) throws QueryException {
 
+    final byte[] modUri = Token.eq(name.uri(), FN_URI) ? FN_URI : QNm.uri(sc.module);
     final StaticFunc sf = new StaticFunc(name, params, expr, anns, vs, info, doc);
-    if(!cache(name.prefixId()).register(sf)) throw DUPLFUNC_X.get(sf.info, name.string());
+    if(get(sc, name, sf.min, sf.arity()) != null) throw DUPLFUNC_X.get(info, name);
+    funcsByModule.computeIfAbsent(modUri, QNmMap::new).computeIfAbsent(name, ArrayList::new).
+        add(sf);
     return sf;
   }
 
   /**
-   * Registers a function call.
-   * @param call name function name
-   * @throws QueryException query exception
+   * Creates a new unresolved function reference.
+   * @param resolve function to resolve the reference
+   * @return unresolved function reference
    */
-  void register(final StaticFuncCall call) throws QueryException {
-    cache(call.name.prefixId()).add(call);
+  public Expr newRef(final QuerySupplier<Expr> resolve) {
+    final FuncRef fr = new FuncRef(resolve);
+    unresolvedRefs.add(fr);
+    return fr;
   }
 
   /**
-   * Registers a closure.
-   * @param closure wrapped literal
+   * Assigns a function to a static function call.
+   * @param call name function name
+   * @param qc query context
+   * @throws QueryException query exception
    */
-  public void register(final Closure closure) {
-    cache(closure.funcName().prefixId()).add(closure);
+  void setFunc(final StaticFuncCall call, final QueryContext qc) throws QueryException {
+    final InputInfo info = call.info();
+    final QNm name = call.name;
+    final int arity = call.arity();
+    final StaticFunc func = get(info.sc(), name, arity);
+    if(func != null) {
+      if(func.expr == null) throw FUNCNOIMPL_X.get(func.info, func.name.prefixString());
+      call.setFunc(func);
+      if(func.updating) qc.updating();
+      // update map for direct lookups of function calls
+      callsMap.computeIfAbsent(func, k -> new ArrayList<>(1)).add(call);
+    } else {
+      final JavaCall java = JavaCall.get(name, call.exprs, qc, info);
+      if(java == null) throw unknownFunctionError(name, arity, info);
+      call.setExternal(java);
+      if(java.updating) qc.updating();
+    }
   }
 
   /**
-   * Checks if all functions have been correctly declared, and initializes all function calls.
-   * @param qc query context
+   * Resolves all function calls.
    * @throws QueryException query exception
    */
-  public void check(final QueryContext qc) throws QueryException {
-    for(final FuncCache cache : caches.values()) cache.init(qc);
+  public void resolve() throws QueryException {
+    for(final FuncRef fr : unresolvedRefs) fr.resolve();
+    unresolvedRefs.clear();
   }
 
   /**
@@ -82,9 +111,7 @@ public void check(final QueryContext qc) throws QueryException {
    * @throws QueryException query exception
    */
   public void checkUp() throws QueryException {
-    for(final FuncCache cache : caches()) {
-      for(final StaticFunc func : cache.funcs) func.checkUp();
-    }
+    for(final StaticFunc func : this) func.checkUp();
   }
 
   /**
@@ -92,22 +119,54 @@ public void checkUp() throws QueryException {
    * @param cc compilation context
    */
   public void compileAll(final CompileContext cc) {
-    for(final FuncCache cache : caches()) {
-      for(final StaticFunc func : cache.funcs) func.compile(cc);
-    }
+    for(final StaticFunc func : this) func.compile(cc);
   }
 
   /**
    * Returns the function with the given name and arity.
+   * @param sc static context
    * @param qname function name
    * @param arity function arity
    * @return function if found, {@code null} otherwise
    */
-  public StaticFunc get(final QNm qname, final long arity) {
-    final FuncCache cache = caches.get(qname.prefixId());
-    if(cache != null) {
-      for(final StaticFunc func : cache.funcs) {
-        if(arity >= func.min && arity <= func.arity()) return func;
+  public StaticFunc get(final StaticContext sc, final QNm qname, final int arity) {
+    return get(sc, qname, arity, arity);
+  }
+
+  /**
+   * Returns a visible function with the given name and arity range.
+   * @param sc static context
+   * @param qname function name
+   * @param min minimum function arity
+   * @param max maximum function arity
+   * @return function if found, {@code null} otherwise
+   */
+  private StaticFunc get(final StaticContext sc, final QNm qname, final int min, final int max) {
+    final byte[] funcUri = qname.uri();
+    final byte[] modUri = Token.eq(funcUri, FN_URI) ? FN_URI : QNm.uri(sc.module);
+    StaticFunc func = get(modUri, qname, min, max);
+    if(func == null && sc.imports.contains(funcUri)) {
+      func = get(funcUri, qname, min, max);
+      if(func != null && func.anns.contains(Annotation.PRIVATE)) func = null;
+    }
+    return func;
+  }
+
+  /**
+   * Returns a function with the given name, and arity in the given range, from the specified
+   * module.
+   * @param modUri module URI
+   * @param qname function name
+   * @param min minimum arity
+   * @param max maximum arity
+   * @return function if found, {@code null} otherwise
+   */
+  private StaticFunc get(final byte[] modUri, final QNm qname, final int min, final int max) {
+    final QNmMap<ArrayList<StaticFunc>> funcsByName = funcsByModule.get(modUri);
+    if(funcsByName != null) {
+      final ArrayList<StaticFunc> funcs = funcsByName.get(qname);
+      if(funcs != null) {
+        for(final StaticFunc func : funcs) if(min <= func.arity() && max >= func.min) return func;
       }
     }
     return null;
@@ -119,15 +178,6 @@ public StaticFunc get(final QNm qname, final long arity) {
    * @return sequence types, or {@code null} if function is not referenced
    */
   SeqType[] seqTypes(final StaticFunc func) {
-    // initialize cache for direct lookups of function calls
-    if(callsMap == null) {
-      callsMap = new IdentityHashMap<>();
-      for(final FuncCache cache : caches()) {
-        for(final StaticFuncCall call : cache.calls) {
-          callsMap.computeIfAbsent(call.func, k -> new ArrayList<>(1)).add(call);
-        }
-      }
-    }
     final ArrayList<StaticFuncCall> calls = callsMap.get(func);
     final int sl = func.arity();
     if(calls == null || calls.isEmpty() || sl == 0) return null;
@@ -142,211 +192,147 @@ SeqType[] seqTypes(final StaticFunc func) {
     return seqTypes;
   }
 
+  /**
+   * Creates an exception for an unknown function.
+   * @param name function name
+   * @param arity function arity
+   * @param info input info
+   * @return query exception
+   */
+  QueryException unknownFunctionError(final QNm name, final int arity,
+      final InputInfo info) {
+
+    final byte[] funcUri = name.uri();
+    final StaticFunc sf = get(funcUri, name, arity, arity);
+    if(sf != null) return sf.anns.contains(Annotation.PRIVATE) ? FUNCPRIVATE_X.get(info, name)
+                                                               : INVISIBLEFUNC_X.get(info, name);
+    final ArrayList<byte[]> modules = new ArrayList<>(2);
+    if(Token.eq(funcUri, FN_URI)) {
+      modules.add(FN_URI);
+    } else {
+      modules.add(QNm.uri(info.sc().module));
+      if(info.sc().imports.contains(funcUri)) modules.add(funcUri);
+    }
+    final IntList arities = new IntList();
+    for(final byte[] module : modules) {
+      final QNmMap<ArrayList<StaticFunc>> funcsByName = funcsByModule.get(module);
+      if(funcsByName != null) {
+        final ArrayList<StaticFunc> funcs = funcsByName.get(name);
+        if(funcs != null) {
+          for(final StaticFunc func : funcs) {
+            for(int a = func.min; a <= func.arity(); ++a) arities.add(a);
+          }
+        }
+      }
+    }
+    return arities.isEmpty()
+        ? similarError(name, info)
+        : Functions.wrongArity(arity, arities, false, info, name.prefixString());
+  }
+
   /**
    * Throws an exception if the name of a function is similar to the specified function name.
    * @param qname function name
    * @param info input info (can be {@code null})
    * @return exception
    */
-  public QueryException similarError(final QNm qname, final InputInfo info) {
+  QueryException similarError(final QNm qname, final InputInfo info) {
     // check local functions
-    final ArrayList<QNm> list = new ArrayList<>();
-    for(final FuncCache cache : caches()) {
-      for(final StaticFunc func : cache.funcs) {
-        if(func.expr != null) {
-          list.add(cache.qname());
-          break;
-        }
-      }
-    }
-    final Object similar = Levenshtein.similar(qname.local(), list.toArray(QNm[]::new),
+    final QNmSet names = new QNmSet();
+    for(final StaticFunc func : this) if(func.expr != null) names.add(func.name);
+    final QNm similar = (QNm) Levenshtein.similar(qname.local(), names.keys(),
         o -> ((QNm) o).local());
 
     // return error for local or global function
     return WHICHFUNC_X.get(info, similar != null ?
-      similar(qname.prefixString(), ((QNm) similar).prefixString()) :
+      similar(qname.prefixString(), similar.prefixString()) :
       Functions.similar(qname));
   }
 
-  /**
-   * Returns all user-defined functions.
-   * @return functions
-   */
-  public StaticFunc[] funcs() {
-    final ArrayList<StaticFunc> list = new ArrayList<>();
-    for(final FuncCache cache : caches()) list.addAll(cache.funcs);
-    return list.toArray(StaticFunc[]::new);
+  @Override
+  public Iterator<StaticFunc> iterator() {
+    return new Iterator<>() {
+      final Iterator<QNmMap<ArrayList<StaticFunc>>> modules = funcsByModule.values().iterator();
+      Iterator<ArrayList<StaticFunc>> names = Collections.emptyIterator();
+      Iterator<StaticFunc> funcs = Collections.emptyIterator();
+
+      @Override public boolean hasNext() {
+        while(!funcs.hasNext()) {
+          if(names.hasNext()) funcs = names.next().iterator();
+          else if(modules.hasNext()) names = modules.next().values().iterator();
+          else return false;
+        }
+        return true;
+      }
+
+      @Override public StaticFunc next() {
+        if(!hasNext()) throw new NoSuchElementException();
+        return funcs.next();
+      }
+    };
   }
 
   @Override
   public void toXml(final QueryPlan plan) {
-    if(!caches.isEmpty()) plan.add(plan.create(this), funcs());
+    if(funcsByModule.isEmpty()) return;
+    final ArrayList<StaticFunc> list = new ArrayList<>();
+    forEach(list::add);
+    plan.add(plan.create(this), list.toArray(StaticFunc[]::new));
   }
 
   @Override
   public void toString(final QueryString qs) {
-    for(final FuncCache cache : caches()) {
-      for(final StaticFunc func : cache.funcs) {
-        if(func.compiled()) qs.token(func).token(Text.NL);
-      }
-    }
-  }
-
-  /**
-   * Returns all user-defined function caches.
-   * @return caches
-   */
-  private ArrayList<FuncCache> caches() {
-    final ArrayList<FuncCache> list = new ArrayList<>();
-    for(final FuncCache cache : caches.values()) {
-      if(!cache.funcs.isEmpty()) list.add(cache);
-    }
-    return list;
+    for(final StaticFunc func : this) if(func.compiled()) qs.token(func).token(Text.NL);
   }
 
   /**
-   * Returns a function cache for the specified function ID.
-   * @param id function ID
-   * @return function cache
+   * A reference to an initially unresolved function call or named function item, to be resolved
+   * after parsing, when all user-defined function declarations have been processed.
    */
-  private FuncCache cache(final byte[] id) {
-    return caches.computeIfAbsent(id, FuncCache::new);
-  }
-
-  /**
-   * Function cache.
-   *
-   * @author BaseX Team, BSD License
-   * @author Christian Gruen
-   */
-  private static final class FuncCache {
-    /** Functions. */
-    final ArrayList<StaticFunc> funcs = new ArrayList<>(1);
-    /** Function calls. */
-    final ArrayList<StaticFuncCall> calls = new ArrayList<>(0);
-    /** Function closures. */
-    final ArrayList<Closure> closures = new ArrayList<>(0);
+  private static final class FuncRef extends Single {
+    /** Function to resolve this reference. */
+    private final QuerySupplier<Expr> resolve;
 
     /**
-     * Initializes the function calls and closures.
-     * @param qc query context
-     * @throws QueryException query exception
+     * Constructor.
+     * @param resolve function to resolve the reference
      */
-    void init(final QueryContext qc) throws QueryException {
-      // assign functions to function calls
-      for(final StaticFuncCall call : calls) {
-        if(call.func == null && !setFunc(call) && !setJava(call, qc)) {
-          // function is unknown: raise error
-          if(!calls.isEmpty()) {
-            final IntList arities = new IntList();
-            for(final StaticFunc func : funcs) arities.add(func.min).add(func.arity());
-            final InputInfo info = call.info();
-            throw arities.isEmpty() ? qc.functions.similarError(qname(), info) :
-              Functions.wrongArity(call.arity(), arities, false, info, qname().prefixString());
-          }
-        } else {
-          // check if all implementations exist for all functions, set updating flag
-          final StaticFunc func = call.func;
-          if(func != null) {
-            if(!call.hasImport) {
-              final QNm funcMod = func.sc.module;
-              final QNm callMod = call.info().sc().module;
-              final byte[] funcModUri = funcMod == null ? Token.EMPTY : funcMod.uri();
-              final byte[] callModUri = callMod == null ? Token.EMPTY : callMod.uri();
-              if(!Token.eq(funcModUri, callModUri)) {
-                throw INVISIBLEFUNC_X.get(call.info(), call.name);
-              }
-            }
-            if(func.updating) qc.updating();
-          } else if(((JavaCall) call.external).updating) qc.updating();
-        }
-      }
-
-      // assign function signatures to function closures
-      for(final Closure closure : closures) {
-        final int arity = closure.arity();
-        for(final StaticFunc func : funcs) {
-          if(arity >= func.min && arity <= func.arity()) {
-            closure.setSignature(func.funcType());
-            break;
-          }
-        }
-      }
+    FuncRef(final QuerySupplier<Expr> resolve) {
+      super(null, null, Types.ITEM_ZM);
+      this.resolve = resolve;
     }
 
     /**
-     * Registers the specified function.
-     * @param func function to assign
-     * @return success flag
+     * Resolves the function reference.
+     * @throws QueryException query exception
      */
-    boolean register(final StaticFunc func) {
-      /* Reject a function with a conflicting arity range. Examples:
-       * f($a), f($b)
-       * f($a), f($a, $b := ()) */
-      final int nargs = func.arity();
-      for(final StaticFunc sf : funcs) {
-        if(nargs >= sf.min && func.min <= sf.arity()) return false;
-      }
-      funcs.add(func);
-      return true;
+    void resolve() throws QueryException {
+      expr = resolve.get();
     }
 
-    /**
-     * Adds a function call.
-     * @param call function call
-     * @throws QueryException query exception
-     */
-    void add(final StaticFuncCall call) throws QueryException {
-      calls.add(call);
-      setFunc(call);
+    @Override
+    public void checkUp() throws QueryException {
+      expr.checkUp();
     }
 
-    /**
-     * Tries to assign a function to a static function call.
-     * @param call static function call
-     * @return success flag
-     * @throws QueryException query exception
-     */
-    boolean setFunc(final StaticFuncCall call) throws QueryException {
-      final int arity = call.arity();
-      for(final StaticFunc func : funcs) {
-        if(arity >= func.min && arity <= func.arity()) {
-          if(func.expr == null) throw FUNCNOIMPL_X.get(func.info, func.name.prefixString());
-          call.setFunc(func);
-          return true;
-        }
-      }
-      return false;
+    @Override
+    public boolean vacuous() {
+      return expr.vacuous();
     }
 
-    /**
-     * Tries to assign a Java function to a static function call.
-     * @param call static function call
-     * @param qc query context
-     * @return success flag
-     * @throws QueryException query exception
-     */
-    boolean setJava(final StaticFuncCall call, final QueryContext qc) throws QueryException {
-      final JavaCall java = closures.isEmpty() ?
-        JavaCall.get(call.name, call.exprs, qc, call.info()) : null;
-      call.setExternal(java);
-      return java != null;
+    @Override
+    public Expr compile(final CompileContext cc) throws QueryException {
+      return expr.compile(cc);
     }
 
-    /**
-     * Adds a closure.
-     * @param closure closure
-     */
-    void add(final Closure closure) {
-      closures.add(closure);
+    @Override
+    public Expr copy(final CompileContext cc, final IntObjectMap<Var> vm) {
+      throw Util.notExpected();
     }
 
-    /**
-     * Returns the function's name.
-     * @return function name
-     */
-    QNm qname() {
-      return funcs.isEmpty() ? calls.get(0).name : funcs.get(0).name;
+    @Override
+    public void toString(final QueryString qs) {
+      expr.toString(qs);
     }
   }
 }
diff --git a/basex-core/src/main/java/org/basex/query/func/fn/FnFunctionLookup.java b/basex-core/src/main/java/org/basex/query/func/fn/FnFunctionLookup.java
index d2ad003139..190e2bb742 100644
--- a/basex-core/src/main/java/org/basex/query/func/fn/FnFunctionLookup.java
+++ b/basex-core/src/main/java/org/basex/query/func/fn/FnFunctionLookup.java
@@ -50,7 +50,7 @@ private Expr item(final QueryContext qc) throws QueryException {
     final long arity = toLong(arg(1), qc);
     if(arity >= 0 && arity <= Integer.MAX_VALUE) {
       try {
-        return Functions.item(name, (int) arity, true, info, qc, true);
+        return Functions.item(name, (int) arity, true, info, qc);
       } catch(final QueryException ex) {
         Util.debug(ex);
       }
diff --git a/basex-core/src/main/java/org/basex/query/func/fn/FnLoadXQueryModule.java b/basex-core/src/main/java/org/basex/query/func/fn/FnLoadXQueryModule.java
index 098a5ee506..7d2cfa4ad5 100644
--- a/basex-core/src/main/java/org/basex/query/func/fn/FnLoadXQueryModule.java
+++ b/basex-core/src/main/java/org/basex/query/func/fn/FnLoadXQueryModule.java
@@ -137,12 +137,12 @@ public XQMap item(final QueryContext qc, final InputInfo ii) throws QueryExcepti
     }
 
     final QNmMap<Map<Integer, Expr>> funcs = new QNmMap<>();
-    for(final StaticFunc sf : mqc.functions.funcs()) {
+    for(final StaticFunc sf : mqc.functions) {
       if(sf.updating()) mqc.updating();
       if(!sf.anns.contains(Annotation.PRIVATE) && Token.eq(sf.name.uri(), modUri)) {
         for(int a = sf.minArity(); a <= sf.arity(); ++a) {
-          final FuncBuilder fb = new FuncBuilder(info, a, true);
-          final Expr item = Functions.item(sf, fb, mqc, true);
+          final FuncBuilder fb = new FuncBuilder(sf.info, a, true);
+          final Expr item = Functions.item(sf, fb, mqc);
           funcs.computeIfAbsent(sf.name, HashMap::new).put(a, item);
         }
       }
diff --git a/basex-core/src/main/java/org/basex/query/func/fn/FnSchemaType.java b/basex-core/src/main/java/org/basex/query/func/fn/FnSchemaType.java
index 26c6c29a53..1fdd6853e8 100644
--- a/basex-core/src/main/java/org/basex/query/func/fn/FnSchemaType.java
+++ b/basex-core/src/main/java/org/basex/query/func/fn/FnSchemaType.java
@@ -105,7 +105,7 @@ protected static Value annotate(final QueryContext qc, final InputInfo info, fin
       if(matches != null) mb.put("matches", matches);
       if(constructor) {
         mb.put("constructor", FuncType.get(Types.ANY_ATOMIC_TYPE_ZM, Types.ANY_ATOMIC_TYPE_ZO).cast(
-            (FuncItem) Functions.item(name, 1, true, info, qc, true), qc, info));
+            (FuncItem) Functions.item(name, 1, true, info, qc), qc, info));
       }
       vb.add(mb.map());
     }
diff --git a/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunction.java b/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunction.java
index 511ada39ad..17275e7330 100644
--- a/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunction.java
+++ b/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunction.java
@@ -1,6 +1,7 @@
 package org.basex.query.func.inspect;
 
 import org.basex.query.*;
+import org.basex.query.ann.*;
 import org.basex.query.func.*;
 import org.basex.query.value.item.*;
 import org.basex.query.value.node.*;
@@ -18,7 +19,20 @@ public FNode item(final QueryContext qc, final InputInfo ii) throws QueryExcepti
     final FItem function = toFunction(arg(0), qc);
 
     final QNm name = function.funcName();
-    final StaticFunc sf = name == null ? null : qc.functions.get(name, function.arity());
-    return new PlainDoc(qc, info).function(name, sf, function.funcType(), function.annotations());
+    StaticFunc func = null;
+    if(name != null) {
+      final int arity = function.arity();
+      func = qc.functions.get(ii.sc(), name, arity);
+      if(func == null) {
+        for(final StaticFunc sf : qc.functions) {
+          if(!sf.annotations().contains(Annotation.PRIVATE) && sf.funcName().eq(name)
+              && sf.minArity() <= arity && sf.arity() >= arity) {
+            func = sf;
+            break;
+          }
+        }
+      }
+    }
+    return new PlainDoc(qc, info).function(name, func, function.funcType(), function.annotations());
   }
 }
diff --git a/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunctions.java b/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunctions.java
index c175038d3b..76a853a01f 100644
--- a/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunctions.java
+++ b/basex-core/src/main/java/org/basex/query/func/inspect/InspectFunctions.java
@@ -27,7 +27,7 @@ public Value value(final QueryContext qc) throws QueryException {
     // returns all functions from the query context
     if(source == null) {
       final ValueBuilder vb = new ValueBuilder(qc);
-      for(final StaticFunc sf : qc.functions.funcs()) {
+      for(final StaticFunc sf : qc.functions) {
         if(!NSGlobal.reserved(sf.name.uri())) addItems(vb, sf, qc);
       }
       return vb.value(this);
@@ -40,7 +40,7 @@ public Value value(final QueryContext qc) throws QueryException {
 
     // cache existing functions
     final HashSet<StaticFunc> old = new HashSet<>();
-    Collections.addAll(old, qc.functions.funcs());
+    qc.functions.forEach(old::add);
 
     try {
       qc.parse(src.toString(), src.path());
@@ -51,7 +51,7 @@ public Value value(final QueryContext qc) throws QueryException {
 
     // collect new functions
     final ValueBuilder vb = new ValueBuilder(qc);
-    for(final StaticFunc sf : qc.functions.funcs()) {
+    for(final StaticFunc sf : qc.functions) {
       if(!old.contains(sf)) addItems(vb, sf, qc);
     }
     funcs = vb.value(this);
@@ -84,7 +84,7 @@ private static void addItems(final ValueBuilder vb, final StaticFunc sf, final Q
     for(int a = sf.minArity(); a <= sf.arity(); ++a) {
       final FuncBuilder fb = new FuncBuilder(sf.info, a, true);
       // safe cast (no context dependency, runtime evaluation)
-      vb.add((FuncItem) Functions.item(sf, fb, qc, true));
+      vb.add((FuncItem) Functions.item(sf, fb, qc));
     }
   }
 }
diff --git a/basex-core/src/main/java/org/basex/query/func/inspect/PlainDoc.java b/basex-core/src/main/java/org/basex/query/func/inspect/PlainDoc.java
index be5f853051..f69ca26688 100644
--- a/basex-core/src/main/java/org/basex/query/func/inspect/PlainDoc.java
+++ b/basex-core/src/main/java/org/basex/query/func/inspect/PlainDoc.java
@@ -40,7 +40,7 @@ final class PlainDoc extends Inspect {
   FNode context() throws QueryException {
     final FBuilder root = element("context");
     for(final StaticVar sv : qc.vars) root.add(variable(sv));
-    for(final StaticFunc sf : qc.functions.funcs()) {
+    for(final StaticFunc sf : qc.functions) {
       if(!NSGlobal.reserved(sf.name.uri())) {
         root.add(function(sf.name, sf, sf.funcType(), sf.anns));
       }
diff --git a/basex-core/src/main/java/org/basex/query/func/unit/Unit.java b/basex-core/src/main/java/org/basex/query/func/unit/Unit.java
index b1afe1b44c..511cd529de 100644
--- a/basex-core/src/main/java/org/basex/query/func/unit/Unit.java
+++ b/basex-core/src/main/java/org/basex/query/func/unit/Unit.java
@@ -83,7 +83,7 @@ public void test(final FBuilder suites) throws IOException {
       qc.parse(input, file.path());
 
       // loop through all functions
-      for(final StaticFunc sf : qc.functions.funcs()) {
+      for(final StaticFunc sf : qc.functions) {
         // find Unit annotations
         final AnnList anns = sf.anns;
         boolean unit = false;
diff --git a/basex-core/src/main/java/org/basex/query/util/parse/LocalVars.java b/basex-core/src/main/java/org/basex/query/util/parse/LocalVars.java
index 26855447d5..d9026543b3 100644
--- a/basex-core/src/main/java/org/basex/query/util/parse/LocalVars.java
+++ b/basex-core/src/main/java/org/basex/query/util/parse/LocalVars.java
@@ -102,7 +102,7 @@ public ParseExpr resolve(final QNm name, final InputInfo info) throws QueryExcep
     // - if a variable uses the module or an imported URI, or
     // - if it is specified in the main module
     final QNm module = parser.sc.module;
-    final boolean hasImport = parser.moduleURIs.contains(uri);
+    final boolean hasImport = parser.sc.imports.contains(uri);
     if(module == null || eq(module.uri(), uri) || hasImport)
       return parser.qc.vars.newRef(name, info, hasImport);
 
diff --git a/basex-core/src/main/java/org/basex/query/value/item/QNm.java b/basex-core/src/main/java/org/basex/query/value/item/QNm.java
index 4454358b31..1237e6d8fa 100644
--- a/basex-core/src/main/java/org/basex/query/value/item/QNm.java
+++ b/basex-core/src/main/java/org/basex/query/value/item/QNm.java
@@ -146,6 +146,15 @@ public byte[] uri() {
     return uri == null ? Token.EMPTY : uri;
   }
 
+  /**
+   * Returns the URI of the given QName, or an empty string if {@code null}.
+   * @param qnm name (can be {@code null})
+   * @return URI
+   */
+  public static byte[] uri(final QNm qnm) {
+    return qnm == null ? Token.EMPTY : qnm.uri();
+  }
+
   /**
    * Checks if the URI of this QName has been explicitly set.
    * @return result of check
diff --git a/basex-core/src/test/java/org/basex/query/ModuleTest.java b/basex-core/src/test/java/org/basex/query/ModuleTest.java
index fd03e5bab9..2d8fa1058f 100644
--- a/basex-core/src/test/java/org/basex/query/ModuleTest.java
+++ b/basex-core/src/test/java/org/basex/query/ModuleTest.java
@@ -145,6 +145,59 @@ public final class ModuleTest extends SandboxTest {
         + "', '" + o.path() + "') })", QueryError.MODULE_FOUND_OTHER_X_X);
   }
 
+  /** Tests function visibility. */
+  @Test public void functionVisibility() {
+    final IOFile sandbox = sandbox();
+    final IOFile p = new IOFile(sandbox, "p.xqm");
+    write(p, "module namespace p = 'p';\n"
+        + "declare %private function p:x() {'module'};\n"
+        + "declare function p:f() {p:x()};");
+    final IOFile q1 = new IOFile(sandbox, "q1.xqm");
+    write(q1, "module namespace q = 'q';\n"
+        + "declare function q:f() {x()};");
+    final IOFile q2 = new IOFile(sandbox, "q2.xqm");
+    write(q2, "module namespace q = 'q';\n"
+        + "declare %private function x() {42};");
+    final IOFile r = new IOFile(sandbox, "r.xqm");
+    write(r, "module namespace r = 'r';\n"
+        + "declare function r:f() {\n"
+        + "  fn:divided-decimals-record(1, 2),\n"
+        + "  fn:divided-decimals-record#2(3, 4),\n"
+        + "  5 => fn:divided-decimals-record(6),\n"
+        + "  function-lookup(#fn:divided-decimals-record, 2)(7, 8)\n"
+        + "};");
+    final IOFile s = new IOFile(sandbox, "s.xqm");
+    write(s, "module namespace s = 's';\n"
+        + "import module 's' at '" + s.path() + "';\n"
+        + "declare function s:f() {s:x()};");
+
+    // private function does not clash with the same name in another module
+    query("import module namespace p = 'p' at '" + p.path() + "';\n"
+        + "declare function p:x() {'main'};\n"
+        + "p:f(), p:x()", "module\nmain");
+
+    // private function is visible throughout module, even in different file
+    query("import module namespace q = 'q' at '" + q1.path() + "', '" + q2.path() + "';\n"
+        + "q:f()", 42);
+
+    // built-in record constructor visible in library module
+    query("import module namespace r = 'r' at '" + r.path() + "';\n"
+        + "r:f()",
+          "{\"quotient\":1,\"remainder\":2}\n"
+        + "{\"quotient\":3,\"remainder\":4}\n"
+        + "{\"quotient\":5,\"remainder\":6}\n"
+        + "{\"quotient\":7,\"remainder\":8}");
+
+    // private function reported as such
+    error("import module namespace p = 'p' at '" + p.path() + "';\n"
+        + "p:x()", QueryError.FUNCPRIVATE_X);
+
+    // function in main module is not visible in imported module
+    error("import module namespace s = 's' at '" + s.path() + "';\n"
+        + "declare function s:x() {42};\n"
+        + "s:f()", QueryError.WHICHFUNC_X);
+  }
+
   /** Tests rejection of functions and variables, when their modules are not explicitly imported. */
   @Test public void gh2048() {
     final IOFile sandbox = sandbox();
@@ -157,13 +210,11 @@ public final class ModuleTest extends SandboxTest {
         + "};\n"
         + "declare variable $c:hello := 'can you see me now';");
 
-    // function is still visible to fn:function-lookup
+    // function is not visible to fn:function-lookup (not in dynamically known function definitions)
     query("import module namespace b = 'b'  at '" + b.path() + "';\n"
-        + "declare namespace c = 'c';\n"
-        + "fn:function-lookup(xs:QName('c:hello'), 0)()", "can you see me now");
+        + "fn:function-lookup(#Q{c}hello, 0)", "");
     // function is still visible to inspect:functions
     query("import module namespace b  = 'b'  at '" + b.path() + "';\n"
-        + "declare namespace c = 'c';\n"
         + "inspect:functions()", "Q{c}hello#0");
 
     error("import module namespace b = 'b'  at '" + b.path() + "';\n"