diff --git a/src/mbyte.c b/src/mbyte.c
index 7bc184b..f85d5ad 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -4357,7 +4357,7 @@
 	else
 	    s = p + 1;
     }
-    for (i = 0; s[i] != NUL && i < (int)sizeof(buf) - 1; ++i)
+    for (i = 0; i < (int)sizeof(buf) - 1 && s[i] != NUL; ++i)
     {
 	if (s[i] == '_' || s[i] == '-')
 	    buf[i] = '-';