diff --git a/Common/make/ghdl.mk b/Common/make/ghdl.mk
index 42f40bd..2b16fd7 100644
--- a/Common/make/ghdl.mk
+++ b/Common/make/ghdl.mk
@@ -13,7 +13,7 @@ IEEE_STD ?= standard
 RUN_TIME ?= 1000ns
 
 # Build path
-BUILD_DIR := build/$(TARGET)
+BUILD_DIR ?= build/$(TARGET)
 
 # Can be pre-initialized by user
 RUN_OPTS += --stop-time=$(RUN_TIME)