diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/threadsafety/GuardedByUtils.java b/core/src/main/java/com/google/errorprone/bugpatterns/threadsafety/GuardedByUtils.java
index ee472cb6110..fc0b450646a 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/threadsafety/GuardedByUtils.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/threadsafety/GuardedByUtils.java
@@ -95,7 +95,7 @@ static JCTree.JCExpression parseString(String guardedByString, Context context)
   abstract static class GuardedByValidationResult {
     abstract String message();
 
-    abstract Boolean isValid();
+    abstract boolean isValid();
 
     static GuardedByValidationResult invalid(String message) {
       return new AutoValue_GuardedByUtils_GuardedByValidationResult(message, false);