--- old/make/ZipSource.gmk	2017-10-05 11:55:58.576803194 +0200
+++ new/make/ZipSource.gmk	2017-10-05 11:55:58.336806982 +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.