diff --git a/core/definitions.mk b/core/definitions.mk
index e276887..37f7d9d 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1785,7 +1785,9 @@
 define initialize-package-file
 @mkdir -p $(dir $(2))
 $(hide) cp -f $(1) $(2)
-$(hide) zip -qd $(2) "*.class" "*/" || true # Ignore the error when nothing to delete.
+$(hide) zip -qd $(2) "*.class" \
+    $(if $(strip $(PRIVATE_DONT_DELETE_JAR_DIRS)),,"*/") \
+    || true # Ignore the error when nothing to delete.
 endef
 
 #TODO: we kinda want to build different asset packages for