diff --git a/util/m5/m5.c b/util/m5/m5.c
index 118ac94479..8e6f4fc59b 100644
--- a/util/m5/m5.c
+++ b/util/m5/m5.c
@@ -122,7 +122,7 @@ read_file(int dest_fid)
     }
 }
 
-int
+void
 write_file(const char *filename)
 {
     fprintf(stderr, "opening %s\n", filename);