diff --git a/core/definitions.mk b/core/definitions.mk
index 9943d5f..f82bfa5 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1999,6 +1999,19 @@
   ,)
 endef
 
+###########################################################
+## Expand a module name list with REQUIRED modules
+###########################################################
+# $(1): The variable name that holds the initial module name list.
+#       the variable will be modified to hold the expanded results.
+# $(2): The initial module name list.
+# Returns empty string (maybe with some whitespaces).
+define expand-required-modules
+$(eval _erm_new_modules := $(sort $(filter-out $($(1)),\
+  $(foreach m,$(2),$(ALL_MODULES.$(m).REQUIRED)))))\
+$(if $(_erm_new_modules),$(eval $(1) += $(_erm_new_modules))\
+  $(call expand-required-modules,$(1),$(_erm_new_modules)))
+endef
 
 ###########################################################
 ## Other includes
diff --git a/core/main.mk b/core/main.mk
index c22c967..fa56b83 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -546,13 +546,9 @@
   # The base list of modules to build for this product is specified
   # by the appropriate product definition file, which was included
   # by product_config.make.
-  user_PACKAGES := $(call module-installed-files, \
-                       $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PACKAGES))
-  ifeq (0,1)
-    $(info user packages for $(TARGET_DEVICE) ($(INTERNAL_PRODUCT)):)
-    $(foreach p,$(user_PACKAGES),$(info :   $(p)))
-    $(error done)
-  endif
+  user_PACKAGES := $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PACKAGES)
+  $(call expand-required-modules,user_PACKAGES,$(user_PACKAGES))
+  user_PACKAGES := $(call module-installed-files, $(user_PACKAGES))
 else
   # We're not doing a full build, and are probably only including
   # a subset of the module makefiles.  Don't try to build any modules
diff --git a/core/tasks/vendor_module_check.mk b/core/tasks/vendor_module_check.mk
index 65c4258..d26a045 100644
--- a/core/tasks/vendor_module_check.mk
+++ b/core/tasks/vendor_module_check.mk
@@ -30,21 +30,8 @@
 
 ifneq (,$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_RESTRICT_VENDOR_FILES))
 
-_check_modules := $(sort $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PACKAGES))
-
-# expand with the required modules
-# $(1) the module name set to expand
-define _expand_required_modules
-$(eval _erm_new_modules:=)\
-$(foreach m, $(1), $(eval r:=$(ALL_MODULES.$(m).REQUIRED))\
-  $(if $(r), $(if $(filter $(_check_modules), $(r)),,\
-    $(eval _check_modules := $(_check_modules) $(r))\
-    $(eval _erm_new_modules := $(_erm_new_modules) $(r)))))\
-$(if $(_erm_new_modules), $(call _expand_required_modules, $(_erm_new_modules)))
-endef
-
-$(call _expand_required_modules, $(_check_modules))
-
+_vendor_check_modules := $(sort $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PACKAGES))
+$(call expand-required-modules,_vendor_check_modules,$(_vendor_check_modules))
 
 # Restrict owners
 ifneq (,$(filter true owner all, $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_RESTRICT_VENDOR_FILES)))
@@ -58,7 +45,7 @@
     $(filter vendor/%, $(PRODUCT_COPY_FILES)))
 endif
 
-$(foreach m, $(_check_modules), \
+$(foreach m, $(_vendor_check_modules), \
   $(if $(filter vendor/%, $(ALL_MODULES.$(m).PATH)),\
     $(if $(filter $(_vendor_owner_whitelist), $(ALL_MODULES.$(m).OWNER)),,\
       $(error Error: vendor module "$(m)" in $(ALL_MODULES.$(m).PATH) with unknown owner \
@@ -70,7 +57,7 @@
 # Restrict paths
 ifneq (,$(filter path all, $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_RESTRICT_VENDOR_FILES)))
 
-$(foreach m, $(_check_modules), \
+$(foreach m, $(_vendor_check_modules), \
   $(if $(filter vendor/%, $(ALL_MODULES.$(m).PATH)),\
     $(if $(filter $(TARGET_OUT_VENDOR)/%, $(ALL_MODULES.$(m).INSTALLED)),,\
       $(error Error: vendor module "$(m)" in $(ALL_MODULES.$(m).PATH) \
@@ -79,4 +66,5 @@
 
 endif
 
+_vendor_check_modules :=
 endif