diff --git a/Makefile b/Makefile
index b4c9aa00..9d0bc3b1 100644
--- a/Makefile
+++ b/Makefile
@@ -225,7 +225,7 @@ endif
 TCC_GIT_HASH=$(shell git rev-parse > /dev/null 2>&1 && git rev-parse --short HEAD || echo no)
 ifneq ($(TCC_GIT_HASH),no)
 MODIFIED = $(shell git diff | grep --quiet +++ && echo "modified ")
-$(X)tcc.o : DEFINES +=  += -DTCC_GIT_HASH="\"$(MODIFIED)$(TCC_GIT_HASH)\""
+$(X)tcc.o : DEFINES +=  -DTCC_GIT_HASH="\"$(MODIFIED)$(TCC_GIT_HASH)\""
 endif
 
 ifeq ($(CONFIG_debug),yes)