diff --git a/src/java_tools/junitrunner/java/com/google/testing/coverage/ClassProbesMapper.java b/src/java_tools/junitrunner/java/com/google/testing/coverage/ClassProbesMapper.java
index 0633e1acf23794..25c5d105e499c9 100644
--- a/src/java_tools/junitrunner/java/com/google/testing/coverage/ClassProbesMapper.java
+++ b/src/java_tools/junitrunner/java/com/google/testing/coverage/ClassProbesMapper.java
@@ -52,7 +52,7 @@ public Map<Integer, BranchExp> result() {
   public ClassProbesMapper(String className) {
     classLineToBranchExp = new TreeMap<Integer, BranchExp>();
     stringPool = new StringPool();
-    className = stringPool.get(className);
+    this.className = stringPool.get(className);
   }
 
   @Override