diff --git a/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java b/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
index 736082b0022..4767cf6d25d 100644
--- a/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
+++ b/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
@@ -1310,7 +1310,8 @@ public class ExpressionCodegen extends JetVisitor {
             Type type = typeMapper.jvmType((ClassDescriptor) descriptor, OwnerKind.INTERFACE);
             v.instanceOf(type);
         }
-        myStack.push(StackValue.onStack(Type.BOOLEAN_TYPE));
+        StackValue value = StackValue.onStack(Type.BOOLEAN_TYPE);
+        myStack.push(expression.isNot() ? StackValue.not(value) : value);
     }
 
     private void newTypeInfo(JetType jetType) {
diff --git a/idea/src/org/jetbrains/jet/lang/psi/JetIsExpression.java b/idea/src/org/jetbrains/jet/lang/psi/JetIsExpression.java
index a4e8ffb2a33..b3fa7f19d54 100644
--- a/idea/src/org/jetbrains/jet/lang/psi/JetIsExpression.java
+++ b/idea/src/org/jetbrains/jet/lang/psi/JetIsExpression.java
@@ -3,6 +3,8 @@ package org.jetbrains.jet.lang.psi;
 import com.intellij.lang.ASTNode;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.JetNodeTypes;
+import org.jetbrains.jet.lexer.JetTokens;
 
 /**
  * @author abreslav
@@ -27,4 +29,13 @@ public class JetIsExpression extends JetExpression {
         return findChildByClass(JetPattern.class);
     }
 
+    @NotNull
+    public JetSimpleNameExpression getOperationReference() {
+        return (JetSimpleNameExpression) findChildByType(JetNodeTypes.OPERATION_REFERENCE);
+    }
+
+    public boolean isNot() {
+        return getOperationReference().getReferencedNameElementType() == JetTokens.NOT_IS;
+    }
+
 }
diff --git a/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java b/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
index d9f7a070b07..998704da068 100644
--- a/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
+++ b/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
@@ -52,6 +52,13 @@ public class TypeInfoTest extends CodegenTestCase {
         assertFalse((Boolean) foo.invoke(null));
     }
 
+    public void testNotIsOperator() throws Exception {
+        loadText("fun foo(x: Any) = x !is Runnable");
+        Method foo = generateFunction();
+        assertTrue((Boolean) foo.invoke(null, new Object()));
+        assertFalse((Boolean) foo.invoke(null, newRunnable()));
+    }
+
     private Runnable newRunnable() {
         return new Runnable() {
             @Override