diff --git a/make/common/JavaCompilation.gmk b/make/common/JavaCompilation.gmk
index a412043bc7bbd..ca363f7cb5474 100644
--- a/make/common/JavaCompilation.gmk
+++ b/make/common/JavaCompilation.gmk
@@ -294,7 +294,10 @@ define SetupJavaCompilationBody
         #
 
     $1_EXTRA_DEPS := $$(BUILDTOOLS_OUTPUTDIR)/depend/_the.COMPILE_DEPEND_batch
-    $1_AUGMENTED_CLASSPATH += $$(BUILDTOOLS_OUTPUTDIR)/depend
+    # including the compilation output on the classpath, so that incremental
+    # compilations in unnamed module can refer to other classes from the same
+    # source root, which are not being recompiled in this compilation:
+    $1_AUGMENTED_CLASSPATH += $$(BUILDTOOLS_OUTPUTDIR)/depend $$($1_BIN)
   endif
 
   ifneq ($$($1_AUGMENTED_CLASSPATH), )
diff --git a/make/test/BuildMicrobenchmark.gmk b/make/test/BuildMicrobenchmark.gmk
index 844c62558dac9..61c84b31a22d6 100644
--- a/make/test/BuildMicrobenchmark.gmk
+++ b/make/test/BuildMicrobenchmark.gmk
@@ -93,7 +93,7 @@ $(eval $(call SetupJavaCompilation, BUILD_INDIFY, \
 $(eval $(call SetupJavaCompilation, BUILD_JDK_MICROBENCHMARK, \
     TARGET_RELEASE := $(TARGET_RELEASE_NEWJDK_UPGRADED), \
     SMALL_JAVA := false, \
-    CLASSPATH := $(JMH_COMPILE_JARS) $(MICROBENCHMARK_CLASSES), \
+    CLASSPATH := $(JMH_COMPILE_JARS), \
     CREATE_API_DIGEST := true, \
     DISABLED_WARNINGS := restricted this-escape processing rawtypes removal cast \
         serial preview dangling-doc-comments, \