diff --git a/awlite.awk b/awlite.awk
index 8f76ffc..3daf568 100644
--- a/awlite.awk
+++ b/awlite.awk
@@ -108,7 +108,7 @@ function mysrand(seed) {
 function myrand(r) {
   if(game["use_native_rand"] > 0) return int(rand() * 65536)
   else { # attempt to optimize McDonnell's generator
-    r = (rng_lastrand * 3677 + 3680) % 2147483647
+    r = (rng_lastrand * 3677 + 3680) % 2147483648
     rng_lastrand = r -1
     return r
   }