1 files changed, 1 insertions, 1 deletions
diff --git a/vm.c b/vm.c
index 158d58f..ac0a52a 100644
--- a/vm.c
+++ b/vm.c
@@ -119,7 +119,7 @@ static match_t *_match(grammar_t *g, file_t *f, const char *str, vm_op_t *op, un
             return m;
         }
         case VM_RANGE: {
-            if (*str < op->args.range.low || *str > op->args.range.high)
+            if ((unsigned char)*str < op->args.range.low || (unsigned char)*str > op->args.range.high)
                 return NULL;
             match_t *m = calloc(sizeof(match_t), 1);
             m->op = op;