diff --git a/src/modal.c b/src/modal.c
index 151b42a..eb90197 100644
--- a/src/modal.c
+++ b/src/modal.c
@@ -128,7 +128,7 @@ write_rule(Rule *r, char last, char *res)
 			put_reg(*b++);
 		else
 			*dst_++ = c, last = c;
-	if(dst_ - origin == 0)
+	if(dst_ == origin)
 		while(*res == ' ') res++;
 	return commit_rule(r, res, 0);
 }