diff --git a/scripts/platform.device.mak b/scripts/platform.device.mak
index 4c6be1d4c..ed95acbfc 100644
--- a/scripts/platform.device.mak
+++ b/scripts/platform.device.mak
@@ -6,4 +6,4 @@ EPSILON_BOOT_PROMPT = update
 EPSILON_DEVICE_BENCH ?= 1
 SFLAGS += -DEPSILON_DEVICE_BENCH=$(EPSILON_DEVICE_BENCH)
 
-python/port/port.o: CXXFLAGS += -DMP_PORT_USE_STACK_SYMBOLS=1
+$(BUILD_DIR)/python/port/port.o: CXXFLAGS += -DMP_PORT_USE_STACK_SYMBOLS=1