diff --git a/util/flex/proto.make b/util/flex/proto.make
index dae3525e0..05f6cd832 100644
--- a/util/flex/proto.make
+++ b/util/flex/proto.make
@@ -99,6 +99,7 @@ flex : $(FLEXOBJS)
 
 first_flex:
 	cp $(SRC_DIR)/initscan.c scan.c
+	chmod +w scan.c
 	make $(MFLAGS) flex
 
 parse.h parse.c : $(SRC_DIR)/parse.y