diff --git a/src/test/java/org/apache/commons/lang3/exception/ExceptionUtilsTest.java b/src/test/java/org/apache/commons/lang3/exception/ExceptionUtilsTest.java
index 10fd6af2c..767e3d9d9 100644
--- a/src/test/java/org/apache/commons/lang3/exception/ExceptionUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/exception/ExceptionUtilsTest.java
@@ -67,7 +67,7 @@ public class ExceptionUtilsTest {
         }
 
         @Override
-        public Throwable getCause() {
+        public synchronized Throwable getCause() {
             return cause;
         }