diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterface.java b/core/src/main/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterface.java
index e22246c5b51..c3528cbae7a 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterface.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterface.java
@@ -17,6 +17,8 @@
 package com.google.errorprone.bugpatterns;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.Streams.findLast;
+import static com.google.common.collect.Streams.stream;
 import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
 import static com.google.errorprone.util.ASTHelpers.getReceiver;
 import static com.google.errorprone.util.ASTHelpers.getSymbol;
@@ -25,7 +27,6 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableMultimap;
-import com.google.common.collect.Streams;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
@@ -231,11 +232,11 @@ private boolean methodCallsMeetConditions(Symbol sym, VisitorState state) {
   }
 
   private static ClassTree getTopLevelClassTree(VisitorState state) {
-    return (ClassTree)
-        Streams.findLast(
-                Streams.stream(state.getPath().iterator())
-                    .filter((Tree t) -> t.getKind() == Kind.CLASS))
-            .orElseThrow(() -> new IllegalArgumentException("No enclosing class found"));
+    return findLast(
+            stream(state.getPath().iterator())
+                .filter(ClassTree.class::isInstance)
+                .map(ClassTree.class::cast))
+        .orElseThrow(() -> new IllegalArgumentException("No enclosing class found"));
   }
 
   private ImmutableMultimap<String, MethodInvocationTree> methodCallsForSymbol(
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterfaceTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterfaceTest.java
index b9429a4a4ab..ccc8087c3cf 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterfaceTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/LambdaFunctionalInterfaceTest.java
@@ -19,7 +19,6 @@
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.CompilationTestHelper;
-import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -27,17 +26,12 @@
 /** {@link LambdaFunctionalInterface}Test */
 @RunWith(JUnit4.class)
 public class LambdaFunctionalInterfaceTest {
-  CompilationTestHelper compilationHelper;
+  private final CompilationTestHelper compilationHelper =
+      CompilationTestHelper.newInstance(LambdaFunctionalInterface.class, getClass());
 
   private final BugCheckerRefactoringTestHelper refactoringHelper =
       BugCheckerRefactoringTestHelper.newInstance(LambdaFunctionalInterface.class, getClass());
 
-  @Before
-  public void setUp() {
-    compilationHelper =
-        CompilationTestHelper.newInstance(LambdaFunctionalInterface.class, getClass());
-  }
-
   @Test
   public void testPositiveCase() {
     compilationHelper.addSourceFile("LambdaFunctionalInterfacePositiveCases.java").doTest();
@@ -215,4 +209,18 @@ public void testRefactoringGenericToPrimitive() {
         .setFixChooser(FixChoosers.FIRST)
         .doTest();
   }
+
+  @Test
+  public void onEnum() {
+    compilationHelper
+        .addSourceLines(
+            "E.java",
+            "import java.util.function.Function;",
+            "public enum E {",
+            "  VALUE(String::length);",
+            "  // BUG: Diagnostic contains:",
+            "  E(Function<String, Integer> func) {}",
+            "}")
+        .doTest();
+  }
 }