1 files changed, 1 insertions, 1 deletions

diff --git a/ltablib.c b/ltablib.c
index d344a47e..c7f0e4dc 100644
--- a/ltablib.c
+++ b/ltablib.c
@@ -146,7 +146,7 @@ static int tmove (lua_State *L) {
 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
   lua_geti(L, 1, i);
   if (!lua_isstring(L, -1))
-    luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
+    luaL_error(L, "invalid value (%s) at index %I in table for 'concat'",
                   luaL_typename(L, -1), i);
   luaL_addvalue(b);
 }