diff --git a/src/test/java/org/elasticsearch/shield/crypto/InternalCryptoServiceTests.java b/src/test/java/org/elasticsearch/shield/crypto/InternalCryptoServiceTests.java
index 3939e314a34..3c184e89bf0 100644
--- a/src/test/java/org/elasticsearch/shield/crypto/InternalCryptoServiceTests.java
+++ b/src/test/java/org/elasticsearch/shield/crypto/InternalCryptoServiceTests.java
@@ -223,7 +223,12 @@ public class InternalCryptoServiceTests extends ElasticsearchTestCase {
         assertThat(Arrays.equals(encrypted, bytes), is(false));
 
         int tamperedIndex = randomIntBetween(0, encrypted.length - 1);
-        encrypted[tamperedIndex] = randomByte();
+        final byte untamperedByte = encrypted[tamperedIndex];
+        byte tamperedByte = randomByte();
+        while (tamperedByte == untamperedByte) {
+            tamperedByte = randomByte();
+        }
+        encrypted[tamperedIndex] = tamperedByte;
         final byte[] decrypted = service.decrypt(encrypted);
         assertThat(Arrays.equals(bytes, decrypted), is(false));
     }