diff --git a/racket/src/racket/src/numstr.c b/racket/src/racket/src/numstr.c
index d3f78e7a41..a3095c5ba2 100644
--- a/racket/src/racket/src/numstr.c
+++ b/racket/src/racket/src/numstr.c
@@ -2115,7 +2115,7 @@ Scheme_Object *scheme_bytes_to_integer(char *str, int slen, int sgned, int rshft
   switch(slen) {
   case 1:
     if (sgned) {
-      char val;
+      signed char val;
       memcpy(&val, str, sizeof(char));
       return scheme_make_integer(val);
     } else {