--- old/test/jdk/java/math/BigInteger/ModPow.java	2018-12-19 17:51:09.000000000 -0800
+++ new/test/jdk/java/math/BigInteger/ModPow.java	2018-12-19 17:51:09.000000000 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,7 +33,9 @@
         Random rnd = new Random(1234);
 
         for (int i=0; i<2000; i++) {
-            BigInteger m = new BigInteger(800, rnd);
+            // Clamp random modulus to non-negative or modPow() will throw
+            // an ArithmeticException.
+            BigInteger m = new BigInteger(800, rnd).max(BigInteger.ONE);
             BigInteger base = new BigInteger(16, rnd);
             if (rnd.nextInt() % 1 == 0)
                 base = base.negate();