diff --git a/protobuf/Makefile b/protobuf/Makefile
index b4e209aaa..cb71a62a1 100644
--- a/protobuf/Makefile
+++ b/protobuf/Makefile
@@ -78,7 +78,7 @@ $(obj)/%.pb-c.c $(obj)/%.pb-c.h: $(obj)/%.proto $(obj)/%.proto.c.d
 	$(E) "  PBCC    " $@
 	$(Q) protoc-c --proto_path=$(obj)/ --c_out=$(obj)/ $<
 ifeq ($(ARCH),arm)
-	$(Q) sed -i 's/4294967295/0xFFFFFFFF/g' $@ $(patsubst %c,%h,$@)
+	$(Q) sed -i -e 's/4294967295/0xFFFFFFFF/g' $@ $(patsubst %.h,%.c,$@)
 endif
 
 $(obj)/%.o: $(obj)/%.pb-c.c $(obj)/%.pb-c.h