diff --git a/src/main/java/hudson/remoting/JarLoaderImpl.java b/src/main/java/hudson/remoting/JarLoaderImpl.java
index e15c4a949..560f97e21 100644
--- a/src/main/java/hudson/remoting/JarLoaderImpl.java
+++ b/src/main/java/hudson/remoting/JarLoaderImpl.java
@@ -5,6 +5,7 @@
 import java.io.IOException;
 import java.io.NotSerializableException;
 import java.io.OutputStream;
+import java.io.UncheckedIOException;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.util.Collections;
@@ -25,13 +26,10 @@ class JarLoaderImpl implements JarLoader, SerializableOnlyOverRemoting {
 
     private static final Logger LOGGER = Logger.getLogger(JarLoaderImpl.class.getName());
 
-    @SuppressFBWarnings(value = "SE_BAD_FIELD", justification = "TODO needs triage")
-    private final ConcurrentMap<Checksum, URL> knownJars = new ConcurrentHashMap<>();
+    private static final ConcurrentMap<Checksum, URL> KNOWN_JARS = new ConcurrentHashMap<>();
 
-    @SuppressFBWarnings(
-            value = {"DMI_COLLECTION_OF_URLS", "SE_BAD_FIELD"},
-            justification = "TODO needs triage")
-    private final ConcurrentMap<URL, Checksum> checksums = new ConcurrentHashMap<>();
+    @SuppressFBWarnings(value = "DMI_COLLECTION_OF_URLS", justification = "TODO needs triage")
+    private static final ConcurrentMap<URL, Checksum> CHECKSUMS = new ConcurrentHashMap<>();
 
     @SuppressFBWarnings(value = "SE_BAD_FIELD", justification = "TODO needs triage")
     private final Set<Checksum> presentOnRemote = Collections.synchronizedSet(new HashSet<>());
@@ -42,7 +40,7 @@ class JarLoaderImpl implements JarLoader, SerializableOnlyOverRemoting {
             justification = "This is only used for managing the jar cache as files, not URLs.")
     public void writeJarTo(long sum1, long sum2, OutputStream sink) throws IOException, InterruptedException {
         Checksum k = new Checksum(sum1, sum2);
-        URL url = knownJars.get(k);
+        URL url = KNOWN_JARS.get(k);
         if (url == null) {
             throw new IOException("Unadvertised jar file " + k);
         }
@@ -93,16 +91,19 @@ public void notifyJarPresence(long[] sums) {
      * Obtains the checksum for the jar at the specified URL.
      */
     public Checksum calcChecksum(URL jar) throws IOException {
-        Checksum v = checksums.get(jar); // cache hit
-        if (v != null) {
-            return v;
+        try {
+            return CHECKSUMS.computeIfAbsent(jar, u -> {
+                try {
+                    Checksum c = Checksum.forURL(u);
+                    KNOWN_JARS.put(c, u);
+                    return c;
+                } catch (IOException e) {
+                    throw new UncheckedIOException(e);
+                }
+            });
+        } catch (UncheckedIOException e) {
+            throw e.getCause();
         }
-
-        v = Checksum.forURL(jar);
-
-        knownJars.put(v, jar);
-        checksums.put(jar, v);
-        return v;
     }
 
     /**