diff --git a/plat/hisilicon/hikey/platform.mk b/plat/hisilicon/hikey/platform.mk
index d43b20b..3662914 100644
--- a/plat/hisilicon/hikey/platform.mk
+++ b/plat/hisilicon/hikey/platform.mk
@@ -9,11 +9,11 @@
 
 # On Hikey, the TSP can execute from TZC secure area in DRAM (default)
 # or SRAM.
-HIKEY_TSP_RAM_LOCATION	:=	dram
+HIKEY_TSP_RAM_LOCATION	?=	dram
 ifeq (${HIKEY_TSP_RAM_LOCATION}, dram)
   HIKEY_TSP_RAM_LOCATION_ID = HIKEY_DRAM_ID
 else ifeq (${HIKEY_TSP_RAM_LOCATION}, sram)
-  HIKEY_TSP_RAM_LOCATION_ID := HIKEY_SRAM_ID
+  HIKEY_TSP_RAM_LOCATION_ID = HIKEY_SRAM_ID
 else
   $(error "Currently unsupported HIKEY_TSP_RAM_LOCATION value")
 endif