diff --git a/lib/debugger/src/Makefile b/lib/debugger/src/Makefile
index 65ad9d46e7b4..e85f9fd7e1c8 100644
--- a/lib/debugger/src/Makefile
+++ b/lib/debugger/src/Makefile
@@ -87,7 +87,7 @@ APPUP_TARGET = $(EBIN)/$(APPUP_FILE)
 # ----------------------------------------------------
 # FLAGS
 # ----------------------------------------------------
-ERL_COMPILE_FLAGS += -Werror
+ERL_COMPILE_FLAGS += -Werror -I $(ERL_TOP)/lib -pa $(ERL_TOP)/lib/wx/ebin
 
 
 # ----------------------------------------------------
diff --git a/lib/et/src/Makefile b/lib/et/src/Makefile
index 819d28a34340..b386accf5381 100644
--- a/lib/et/src/Makefile
+++ b/lib/et/src/Makefile
@@ -68,7 +68,11 @@ APPUP_TARGET = $(EBIN)/$(APPUP_FILE)
 # ----------------------------------------------------
 # FLAGS
 # ----------------------------------------------------
-ERL_COMPILE_FLAGS += -pa $(ERL_TOP)/lib/et/ebin -I../include -Werror
+ERL_COMPILE_FLAGS += -pa $(ERL_TOP)/lib/et/ebin \
+		     -pa $(ERL_TOP)/lib/wx/ebin \
+		     -I../include \
+		     -I $(ERL_TOP)/lib \
+		     -Werror
 
 # ----------------------------------------------------
 # Special Build Targets
diff --git a/lib/observer/src/Makefile b/lib/observer/src/Makefile
index a678b5acbd56..a07e4feadf8c 100644
--- a/lib/observer/src/Makefile
+++ b/lib/observer/src/Makefile
@@ -125,6 +125,8 @@ ERL_COMPILE_FLAGS += \
 	-I../include \
 	-I ../../et/include \
 	-I ../../../libraries/et/include \
+	-I $(ERL_TOP)/lib \
+	-pa $(ERL_TOP)/lib/wx/ebin \
 	-Werror
 
 # ----------------------------------------------------
diff --git a/lib/reltool/src/Makefile b/lib/reltool/src/Makefile
index 935116322c66..6423cab5649d 100644
--- a/lib/reltool/src/Makefile
+++ b/lib/reltool/src/Makefile
@@ -61,7 +61,8 @@ APPUP_TARGET = $(EBIN)/$(APPUP_FILE)
 
 ERL_COMPILE_FLAGS += +'{parse_transform,sys_pre_attributes}' \
                      +'{attribute,insert,app_vsn,$(APP_VSN)}' \
-		     -Werror
+		     -Werror \
+		     -I $(ERL_TOP)/lib
 
 # ----------------------------------------------------
 # Targets
diff --git a/lib/wx/examples/demo/Makefile b/lib/wx/examples/demo/Makefile
index 63b59ee333df..c67c22fa0861 100644
--- a/lib/wx/examples/demo/Makefile
+++ b/lib/wx/examples/demo/Makefile
@@ -63,7 +63,8 @@ TESTMODS = \
 TESTTARGETS = $(TESTMODS:%=%.beam)
 TESTSRC = $(TESTMODS:%=%.erl)
 
-ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented
+ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented \
+		     -I $(ERL_TOP)/lib -pa $(ERL_TOP)/lib/wx/ebin
 
 # Targets
 $(TYPES):	$(TESTTARGETS)
diff --git a/lib/wx/examples/simple/Makefile b/lib/wx/examples/simple/Makefile
index c5371d839f00..f444451eab2c 100644
--- a/lib/wx/examples/simple/Makefile
+++ b/lib/wx/examples/simple/Makefile
@@ -32,7 +32,8 @@ TESTMODS = hello hello2 minimal menu
 TESTTARGETS = $(TESTMODS:%=%.beam)
 TESTSRC = $(TESTMODS:%=%.erl)
 
-ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented
+ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented \
+		     -I $(ERL_TOP)/lib -pa $(ERL_TOP)/lib/wx/ebin
 
 # Targets
 $(TYPES):	$(TESTTARGETS)
diff --git a/lib/wx/examples/sudoku/Makefile b/lib/wx/examples/sudoku/Makefile
index 6434f6eb51ab..55e108e61042 100644
--- a/lib/wx/examples/sudoku/Makefile
+++ b/lib/wx/examples/sudoku/Makefile
@@ -32,7 +32,8 @@ TESTMODS = sudoku sudoku_board sudoku_game sudoku_gui
 TESTTARGETS = $(TESTMODS:%=%.beam)
 TESTSRC = $(TESTMODS:%=%.erl)
 
-ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented
+ERL_COMPILE_FLAGS += +nowarn_missing_doc +nowarn_missing_spec_documented \
+		     -I $(ERL_TOP)/lib -pa $(ERL_TOP)/lib/wx/ebin
 
 # Targets
 $(TYPES):	$(TESTTARGETS)