1 files changed, 1 insertions, 1 deletions

diff --git a/liolib.c b/liolib.c
index 7d6d51e6..fa6a0939 100644
--- a/liolib.c
+++ b/liolib.c
@@ -39,7 +39,7 @@
 /* Check whether 'mode' matches '[rwa]%+?[L_MODEEXT]*' */
 static int l_checkmode (const char *mode) {
   return (*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&
-         (*mode != '+' || (++mode, 1)) &&  /* skip if char is '+' */
+         (*mode != '+' || ((void)(++mode), 1)) &&  /* skip if char is '+' */
          (strspn(mode, L_MODEEXT) == strlen(mode)));  /* check extensions */
 }