diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/CallStandardMethodIntrinsic.java b/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/CallStandardMethodIntrinsic.java
index d5bc018a9da..2ec496ef415 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/CallStandardMethodIntrinsic.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/CallStandardMethodIntrinsic.java
@@ -17,11 +17,13 @@
 package org.jetbrains.k2js.translate.intrinsic;
 
 import com.google.common.collect.Lists;
+import com.google.dart.compiler.Source;
 import com.google.dart.compiler.backend.js.ast.JsExpression;
 import com.google.dart.compiler.backend.js.ast.JsNameRef;
 import com.google.dart.compiler.util.AstUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.lang.diagnostics.DiagnosticUtils;
 import org.jetbrains.k2js.translate.context.TranslationContext;
 
 import java.util.List;
@@ -51,11 +53,24 @@ public final class CallStandardMethodIntrinsic implements Intrinsic {
                               @NotNull List<JsExpression> arguments,
                               @NotNull TranslationContext context) {
         assert (receiver != null == receiverShouldBeNotNull);
-        assert arguments.size() == expectedParamsNumber;
+        assert arguments.size() == expectedParamsNumber : "Incorrect number of arguments " + arguments.size() + " when expected " + expectedParamsNumber + " on method " + methodName + " " + atLocation(receiver, arguments);
         JsNameRef iteratorFunName = AstUtil.newQualifiedNameRef(methodName);
         return newInvocation(iteratorFunName, composeArguments(receiver, arguments));
     }
 
+    // TODO move to better helper class
+    public static String atLocation(JsExpression expression, List<JsExpression> arguments) {
+        List list = Lists.newArrayList(expression);
+        list.addAll(arguments);
+        for (JsExpression value : arguments) {
+            Source source = value.getSource();
+            if (source != null) {
+                return "at " + source + " " + expression.getSourceLine() + ":" + expression.getSourceLine();
+            }
+        }
+        return "at unknown location";
+    }
+
     @NotNull
     private static List<JsExpression> composeArguments(@Nullable JsExpression receiver, @NotNull List<JsExpression> arguments) {
         if (receiver != null) {