diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StateMerger.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StateMerger.java
index 92fe226049db..fc358c798019 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StateMerger.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StateMerger.java
@@ -239,7 +239,8 @@ class StateMerger {
       List<DfaMemoryStateImpl> compatible = ContainerUtil.filter(statesByEq.get(createPair(var, value)), new Condition<DfaMemoryStateImpl>() {
         @Override
         public boolean value(DfaMemoryStateImpl state2) {
-          return seemCompatible(state, state2, var);
+          return seemCompatible(state, state2, var) && 
+                 state.getVariableState(var).withNullability(Nullness.UNKNOWN).equals(state2.getVariableState(var).withNullability(Nullness.UNKNOWN));
         }
       });
       if (compatible.isEmpty()) {
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/DontForgetInstanceofInfoWhenMerging.java b/java/java-tests/testData/inspection/dataFlow/fixture/DontForgetInstanceofInfoWhenMerging.java
new file mode 100644
index 000000000000..ca2737a1bccd
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/DontForgetInstanceofInfoWhenMerging.java
@@ -0,0 +1,19 @@
+class Some {
+  void foo() {
+    Object o = null;
+    while (equals(3)) {
+      if (equals(2)) {
+        if (o == null) {
+          o = new String();
+        }
+      }
+      if (<warning descr="Condition 'o == null || o instanceof String' is always 'true'">o == null || <warning descr="Condition 'o instanceof String' is always 'true' when reached">o instanceof String</warning></warning>) {
+        System.out.println(o);
+      }
+    }
+  }
+
+
+}
+
+
diff --git a/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java b/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
index ffbb6caa4c5a..e9482f500ee7 100644
--- a/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
@@ -307,6 +307,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   public void testManyDisjunctiveFieldAssignmentsInLoopNotComplex() { doTest(); }
   
   public void testVariablesDiverge() { doTest(); }
+  public void testDontForgetInstanceofInfoWhenMerging() { doTest(); }
   
   public void _testNullCheckBeforeInstanceof() { doTest(); } // http://youtrack.jetbrains.com/issue/IDEA-113220
 }