diff a/make/MainSupport.gmk b/make/MainSupport.gmk
--- a/make/MainSupport.gmk
+++ b/make/MainSupport.gmk
@@ -1,7 +1,7 @@
 #
-# Copyright (c) 2011, 2025, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2011, 2026, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License version 2 only, as
 # published by the Free Software Foundation.  Oracle designates this
@@ -105,10 +105,11 @@
 
 define Clean-java
 	@$(PRINTF) "Cleaning java %s..." "$(if $1,for $(strip $1) )"
 	@$(ECHO) "" $(LOG_DEBUG)
 	$(RM) -r $(JDK_OUTPUTDIR)/modules/$(strip $1)
+	$(RM) -r $(SUPPORT_OUTPUTDIR)/preview/$(strip $1)
 	$(RM) -r $(SUPPORT_OUTPUTDIR)/special_classes/$(strip $1)
 	$(ECHO) " done"
 	$(PRINTF) "Cleaning headers %s..." "$(if $1,for $(strip $1) )"
 	$(RM) -r $(SUPPORT_OUTPUTDIR)/headers/$(strip $1)
 	@$(ECHO) " done"