diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TypeConstraint.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TypeConstraint.java
index 07df81eeaf39..a2e6e02dd89f 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TypeConstraint.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TypeConstraint.java
@@ -192,8 +192,19 @@ public final class TypeConstraint {
       instanceOfTypes = withSuper(this.myInstanceofValues);
       instanceOfTypes.retainAll(withSuper(other.myInstanceofValues));
     }
-    TypeConstraint constraint = StreamEx.of(instanceOfTypes).foldLeft(EMPTY, TypeConstraint::withInstanceofValue);
-    return StreamEx.of(notTypes).foldLeft(constraint, TypeConstraint::withNotInstanceofValue);
+    TypeConstraint constraint = EMPTY;
+    for (DfaPsiType type: instanceOfTypes) {
+      constraint = constraint.withInstanceofValue(type);
+      if (constraint == null) {
+        // Should not happen normally, but may happen with inconsistent hierarchy (e.g. if final class is extended)
+        return EMPTY;
+      }
+    }
+    for (DfaPsiType type: notTypes) {
+      constraint = constraint.withNotInstanceofValue(type);
+      if (constraint == null) return EMPTY;
+    }
+    return constraint;
   }
 
   private static Set<DfaPsiType> withSuper(Set<DfaPsiType> instanceofValues) {
diff --git a/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa.java b/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa.java
new file mode 100644
index 000000000000..f4c87c855f5d
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa.java
@@ -0,0 +1,14 @@
+import java.util.*;
+
+class Foo {
+    final class X {}
+    class Y extends X {}
+    class YY extends X {}
+    interface Z {};
+
+    void test(Object o) {
+        if((o instanceof Y && o instanceof Z) || (o instanceof YY && o instanceof Z)) {
+            o.hashC<caret>
+        }
+    }
+}
diff --git a/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa_after.java b/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa_after.java
new file mode 100644
index 000000000000..0c7f4da09db2
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/completion/normal/InconsistentHierarchyDfa_after.java
@@ -0,0 +1,14 @@
+import java.util.*;
+
+class Foo {
+    final class X {}
+    class Y extends X {}
+    class YY extends X {}
+    interface Z {};
+
+    void test(Object o) {
+        if((o instanceof Y && o instanceof Z) || (o instanceof YY && o instanceof Z)) {
+            o.hashCode()<caret>
+        }
+    }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionDfaTest.groovy b/java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionDfaTest.groovy
index a676336654c9..a5f1c55c38d6 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionDfaTest.groovy
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionDfaTest.groovy
@@ -60,6 +60,7 @@ class NormalCompletionDfaTest extends NormalCompletionTestCase {
   void testNarrowingReturnTypeInVoidContext() { doTest() }
   void testNoUnnecessaryCastDfa() { doTest() }
   void testNoUnnecessaryCastRawDfa() { doTest() }
+  void testInconsistentHierarchyDfa() { doTest() }
   void testNoUnnecessaryCastDeepHierarchy() { doTest() }
   void testInstanceOfAfterFunction() { doTest() }
   void testInstanceOfDisjunction() { doTest() }