diff --git a/ag.cc b/ag.cc
index d5dab7d..abccd25 100644
--- a/ag.cc
+++ b/ag.cc
@@ -706,7 +706,7 @@ fail:
         bool valid = true;
         if (argc == 9)
         {
-            for (int i = 0; i < argc; i++)
+            for (int i = 1; i <= argc; i++)
             {
                 if (!lua_isnumber(L, i))
                 {