--- a/make/ZipSource.gmk	Thu Oct 05 11:02:18 2017 +0200
+++ b/make/ZipSource.gmk	Thu Oct 05 12:41:06 2017 +0200
@@ -33,7 +33,7 @@
 SRC_ZIP_WORK_DIR := $(SUPPORT_OUTPUTDIR)/src
 
 # Hook to include the corresponding custom file, if present.
-$(eval $(call IncludeCustomExtension, , ZipSource.gmk))
+$(eval $(call IncludeCustomExtension, ZipSource.gmk))
 
 ################################################################################
 # Create the directory structure for src.zip using symlinks.