diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
index f637d1ddd55..f595a08fdc5 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
@@ -177,7 +177,13 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
                     context.trace.report(EXPECTED_CONDITION.on(condition));
                 }
                 if (pattern != null) {
-                    newDataFlowInfo.set(checkPatternType(pattern, subjectType, subjectExpression == null, scopeToExtend, context, subjectVariables));
+                    Pair<DataFlowInfo, DataFlowInfo> result = checkPatternType(pattern, subjectType, subjectExpression == null, scopeToExtend, context, subjectVariables);
+                    if (condition.isNegated()) {
+                        newDataFlowInfo.set(Pair.create(result.second, result.first));
+                    }
+                    else {
+                        newDataFlowInfo.set(result);
+                    }
                 }
             }
 
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt2146.jet b/compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt2146.jet
index 579f1095ba5..acf19b90e48 100644
--- a/compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt2146.jet
+++ b/compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt2146.jet
@@ -10,8 +10,7 @@ fun f1(s: Int?): Int {
 
 fun f2(s: Int?): Int {
     return when (s) {
-        is 4 -> s
-        is null -> <!TYPE_MISMATCH!>s<!>
+        !is Int -> <!TYPE_MISMATCH!>s<!>
         else -> s
     }
 }
@@ -38,3 +37,17 @@ fun f5(s: Int?): Int {
         else -> 0
     }
 }
+
+fun f6(s: Int?): Int {
+    return when {
+        s is Int -> s
+        else -> <!TYPE_MISMATCH!>s<!>
+    }
+}
+
+fun f7(s: Int?): Int {
+    return when {
+        s !is Int -> <!TYPE_MISMATCH!>s<!>
+        else -> s
+    }
+}