diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index 0e930ee..478c63c 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -102,6 +102,9 @@
   -include $(LLVM_ROOT_PATH)/llvm.mk
 endif
 
+ART_HOST_CFLAGS :=
+ART_TARGET_CFLAGS :=
+
 # Clang build support.
 
 # Host.
@@ -226,13 +229,13 @@
 ifndef LIBART_IMG_HOST_BASE_ADDRESS
   $(error LIBART_IMG_HOST_BASE_ADDRESS unset)
 endif
-ART_HOST_CFLAGS := $(art_cflags) -DANDROID_SMP=1 -DART_BASE_ADDRESS=$(LIBART_IMG_HOST_BASE_ADDRESS)
+ART_HOST_CFLAGS += $(art_cflags) -DANDROID_SMP=1 -DART_BASE_ADDRESS=$(LIBART_IMG_HOST_BASE_ADDRESS)
 ART_HOST_CFLAGS += -DART_DEFAULT_INSTRUCTION_SET_FEATURES=default
 
 ifndef LIBART_IMG_TARGET_BASE_ADDRESS
   $(error LIBART_IMG_TARGET_BASE_ADDRESS unset)
 endif
-ART_TARGET_CFLAGS := $(art_cflags) -DART_TARGET -DART_BASE_ADDRESS=$(LIBART_IMG_TARGET_BASE_ADDRESS)
+ART_TARGET_CFLAGS += $(art_cflags) -DART_TARGET -DART_BASE_ADDRESS=$(LIBART_IMG_TARGET_BASE_ADDRESS)
 
 ART_HOST_NON_DEBUG_CFLAGS := $(art_host_non_debug_cflags)
 ART_TARGET_NON_DEBUG_CFLAGS := $(art_target_non_debug_cflags)