diff --git a/rng.h b/rng.h
index 20d4871..8033353 100644
--- a/rng.h
+++ b/rng.h
@@ -60,7 +60,7 @@ class Xoroshiro128Random
         if (n <=0) return 0;
         int r =  (int)((n & -n) == n ? (nextLong() & n) - 1 // power of two
                        : (unsigned long long)(((unsigned long long)nextLong() >> 32) * n) >> 32);
-        return r < 0 ? 0 : r;
+        return r >= 0 && r < n ? r : 0;
     }
 
     long long nextLong() {