diff --git a/src/test/java/org/apache/commons/csv/CSVBenchmark.java b/src/test/java/org/apache/commons/csv/CSVBenchmark.java
index 64d3f498..86a345d1 100644
--- a/src/test/java/org/apache/commons/csv/CSVBenchmark.java
+++ b/src/test/java/org/apache/commons/csv/CSVBenchmark.java
@@ -202,7 +202,7 @@ public class CSVBenchmark {
         return callback.count;
     }
 
-    private static class CountingReaderCallback implements org.skife.csv.ReaderCallback {
+    private static final class CountingReaderCallback implements org.skife.csv.ReaderCallback {
         public int count;
 
         @Override
diff --git a/src/test/java/org/apache/commons/csv/PerformanceTest.java b/src/test/java/org/apache/commons/csv/PerformanceTest.java
index c0dff75e..489d7235 100644
--- a/src/test/java/org/apache/commons/csv/PerformanceTest.java
+++ b/src/test/java/org/apache/commons/csv/PerformanceTest.java
@@ -48,7 +48,7 @@ public class PerformanceTest {
     }
 
     // Container for basic statistics
-    private static class Stats {
+    private static final class Stats {
         final int count;
         final int fields;
         Stats(final int c, final int f) {