1 files changed, 1 insertions, 1 deletions

diff --git a/loslib.c b/loslib.c
index 8280331b..4623ad5e 100644
--- a/loslib.c
+++ b/loslib.c
@@ -275,7 +275,7 @@ static int getfield (lua_State *L, const char *key, int d, int delta) {
 static const char *checkoption (lua_State *L, const char *conv,
                                 ptrdiff_t convlen, char *buff) {
   const char *option = LUA_STRFTIMEOPTIONS;
-  int oplen = 1;  /* length of options being checked */
+  unsigned oplen = 1;  /* length of options being checked */
   for (; *option != '\0' && oplen <= convlen; option += oplen) {
     if (*option == '|')  /* next block? */
       oplen++;  /* will check options with next length (+1) */