diff --git a/java/java-tests/testSrc/com/intellij/psi/search/ClassInheritorsTest.java b/java/java-tests/testSrc/com/intellij/psi/search/ClassInheritorsTest.java
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+++ b/java/java-tests/testSrc/com/intellij/psi/search/ClassInheritorsTest.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.psi.search;
+
+import com.intellij.codeInsight.daemon.DaemonAnalyzerTestCase;
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.psi.PsiClass;
+import com.intellij.psi.impl.compiled.ClsClassImpl;
+import com.intellij.psi.impl.source.PsiClassImpl;
+import com.intellij.psi.search.searches.ClassInheritorsSearch;
+import com.intellij.psi.search.searches.DirectClassInheritorsSearch;
+import com.intellij.testFramework.IdeaTestUtil;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ClassInheritorsTest extends DaemonAnalyzerTestCase {
+  @Override
+  protected Sdk getTestProjectJdk() {
+    // there must be src.zip
+    return IdeaTestUtil.getMockJdk17("1.7");
+  }
+
+  public void testClsAndSourcesDoNotMixUp() {
+    PsiClass numberClass = getJavaFacade().findClass("java.lang.Number", GlobalSearchScope.allScope(getProject()));
+    assertTrue(String.valueOf(numberClass), numberClass instanceof ClsClassImpl);
+    PsiClass n2 = (PsiClass)numberClass.getNavigationElement();
+    assertTrue(String.valueOf(n2), n2 instanceof PsiClassImpl);
+    Collection<PsiClass> subClasses = DirectClassInheritorsSearch.search(n2, GlobalSearchScope.allScope(getProject())).findAll();
+    List<String> fqn = subClasses.stream().map(PsiClass::getQualifiedName).sorted().collect(Collectors.toList());
+    assertEquals(fqn.toString(), fqn.size(), new HashSet<>(fqn).size()); // no dups mean no Cls/Psi mixed
+
+    Collection<PsiClass> allSubClasses = ClassInheritorsSearch.search(n2, GlobalSearchScope.allScope(getProject()), true).findAll();
+    List<String> allFqn = allSubClasses.stream().map(PsiClass::getQualifiedName).sorted().collect(Collectors.toList());
+    assertEquals(allFqn.toString(), allFqn.size(), new HashSet<>(allFqn).size());
+  }
+}