diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/expression/PatternTranslator.java b/js/js.translator/src/org/jetbrains/k2js/translate/expression/PatternTranslator.java
index 4ee2d4d5627..e9094fbd2df 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/expression/PatternTranslator.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/expression/PatternTranslator.java
@@ -110,8 +110,8 @@ public final class PatternTranslator extends AbstractTranslator {
     }
 
     @NotNull
-    private JsExpression addNullCheck(@NotNull JsExpression expressionToMatch, @NotNull JsInvocation isCheck) {
-        return or(TranslationUtils.isNullCheck(context(), expressionToMatch), isCheck);
+    private static JsExpression addNullCheck(@NotNull JsExpression expressionToMatch, @NotNull JsInvocation isCheck) {
+        return or(TranslationUtils.isNullCheck(expressionToMatch), isCheck);
     }
 
     private boolean isNullable(JetTypePattern pattern) {
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/reference/CallType.java b/js/js.translator/src/org/jetbrains/k2js/translate/reference/CallType.java
index 45417cc20af..1dcaa3c4f36 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/reference/CallType.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/reference/CallType.java
@@ -42,7 +42,7 @@ public enum CallType {
                                    @NotNull TranslationContext context) {
             assert receiver != null;
             TemporaryVariable temporaryVariable = context.declareTemporary(receiver);
-            JsBinaryOperation notNullCheck = TranslationUtils.notNullCheck(context, temporaryVariable.reference());
+            JsBinaryOperation notNullCheck = TranslationUtils.notNullConditionalTestExpression(temporaryVariable);
             JsExpression methodCall = constructor.construct(temporaryVariable.reference());
             JsConditional callMethodIfNotNullElseNull = new JsConditional(notNullCheck, methodCall, JsNullLiteral.NULL);
             return newSequence(temporaryVariable.assignmentExpression(), callMethodIfNotNullElseNull);
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/utils/TranslationUtils.java b/js/js.translator/src/org/jetbrains/k2js/translate/utils/TranslationUtils.java
index 414a447f7c1..5b363c667db 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/utils/TranslationUtils.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/utils/TranslationUtils.java
@@ -24,6 +24,7 @@ import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.calls.ResolvedCall;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
+import org.jetbrains.k2js.translate.context.TemporaryVariable;
 import org.jetbrains.k2js.translate.context.TranslationContext;
 import org.jetbrains.k2js.translate.general.Translation;
 
@@ -66,19 +67,22 @@ public final class TranslationUtils {
     }
 
     @NotNull
-    public static JsBinaryOperation notNullCheck(@NotNull TranslationContext context,
-            @NotNull JsExpression expressionToCheck) {
-        JsBinaryOperation notNull = inequality(expressionToCheck, JsLiteral.NULL);
-        JsBinaryOperation notUndefined = inequality(expressionToCheck, UNDEFINED_LITERAL);
-        return and(notNull, notUndefined);
+    public static JsBinaryOperation isNullCheck(@NotNull JsExpression expressionToCheck) {
+        return nullCheck(expressionToCheck, false);
     }
 
     @NotNull
-    public static JsBinaryOperation isNullCheck(@NotNull TranslationContext context,
-            @NotNull JsExpression expressionToCheck) {
-        JsBinaryOperation isNull = equality(expressionToCheck, JsLiteral.NULL);
-        JsBinaryOperation isUndefined = equality(expressionToCheck, UNDEFINED_LITERAL);
-        return or(isNull, isUndefined);
+    public static JsBinaryOperation notNullConditionalTestExpression(@NotNull TemporaryVariable cachedValue) {
+        return and(inequality(cachedValue.assignmentExpression(), JsLiteral.NULL),
+                   inequality(cachedValue.reference(), JsLiteral.UNDEFINED));
+    }
+
+    @NotNull
+    public static JsBinaryOperation nullCheck(@NotNull JsExpression expressionToCheck, boolean isNegated) {
+        JsBinaryOperator operator = isNegated ? JsBinaryOperator.REF_NEQ : JsBinaryOperator.REF_EQ;
+        return new JsBinaryOperation(isNegated ? JsBinaryOperator.AND : JsBinaryOperator.OR,
+                                     new JsBinaryOperation(operator, expressionToCheck, JsLiteral.NULL),
+                                     new JsBinaryOperation(operator, expressionToCheck, JsLiteral.UNDEFINED));
     }
 
     @NotNull