diff --git a/Android.mk b/Android.mk
index 42b3438..ccb66e5 100644
--- a/Android.mk
+++ b/Android.mk
@@ -80,9 +80,21 @@
 #    - compile output binary policy file
 
 PLAT_PUBLIC_POLICY := $(LOCAL_PATH)/public
-PLAT_PUBLIC_POLICY += $(BOARD_PLAT_PUBLIC_SEPOLICY_DIRS)
+ifneq ( ,$(BOARD_PLAT_PUBLIC_SEPOLICY_DIR))
+ifneq (1, $(words $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR)))
+$(error BOARD_PLAT_PUBLIC_SEPOLICY_DIR must only contain one directory)
+else
+PLAT_PUBLIC_POLICY += $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR)
+endif
+endif
 PLAT_PRIVATE_POLICY := $(LOCAL_PATH)/private
-PLAT_PRIVATE_POLICY += $(BOARD_PLAT_PRIVATE_SEPOLICY_DIRS)
+ifneq ( ,$(BOARD_PLAT_PRIVATE_SEPOLICY_DIR))
+ifneq (1, $(words $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR)))
+$(error BOARD_PLAT_PRIVATE_SEPOLICY_DIR must only contain one directory)
+else
+PLAT_PRIVATE_POLICY += $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR)
+endif
+endif
 PLAT_VENDOR_POLICY := $(LOCAL_PATH)/vendor
 REQD_MASK_POLICY := $(LOCAL_PATH)/reqd_mask