diff --git a/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java b/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
index f10b89fcb67f..ebff707ebacd 100644
--- a/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
+++ b/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
@@ -541,7 +541,10 @@ public class RedundantCastUtil {
             if (opposite == null || conditionalType instanceof PsiPrimitiveType &&
                                     !Comparing.equal(conditionalType, opposite.getType())) return;
           }
-        } else if (parent instanceof PsiSynchronizedStatement && expr != null && expr.getType() instanceof PsiPrimitiveType) {
+        }
+        else if (parent instanceof PsiSynchronizedStatement &&
+                 expr != null &&
+                 (expr.getType() instanceof PsiPrimitiveType || expr instanceof PsiFunctionalExpression)) {
           return;
         } else if (expr instanceof PsiLambdaExpression || expr instanceof PsiMethodReferenceExpression) {
           if (parent instanceof PsiParenthesizedExpression && parent.getParent() instanceof PsiReferenceExpression) {
diff --git a/java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext.java b/java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext.java
index 3d7a4c5e98fd..e9b30032afb6 100644
--- a/java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext.java
+++ b/java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext.java
@@ -7,6 +7,12 @@ class Test {
     return s.length();
   }
 
+  void test() {
+    synchronized ((Bar)Test::length) {
+      System.out.println("Synchronizing on a method reference is a nice thing to try!");
+    }
+  }
+
   interface Bar {
     Integer m(String s);
   }