diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
index 04d77e86797..2fb1c74abf1 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
@@ -319,6 +319,15 @@ public class DeclarationResolver {
 
     private void checkRedeclarationsInNamespaces() {
         for (MutablePackageFragmentDescriptor packageFragment : Sets.newHashSet(context.getPackageFragments().values())) {
+            if (KotlinBuiltIns.BUILT_INS_PACKAGE_FQ_NAME.equals(packageFragment.getFqName())) {
+                // TODO: drop this after built-ins are fully rewritten to Kotlin
+                // At the moment, there are Java classes for ranges (e.g. IntRange.java) which contain static members. If someone tries to
+                // rewrite IntRange to Kotlin, redeclaration will be reported because there are both class (from the Kotlin sources) and
+                // package (from static members of Java class present in kotlin-runtime.jar) for FQ name "jet.IntRange".
+                // Will be safe to drop once there are no Java classes duplicating sources of Kotlin built-ins
+                continue;
+            }
+
             PackageViewDescriptor packageView = packageFragment.getContainingDeclaration().getPackage(packageFragment.getFqName());
             JetScope packageViewScope = packageView.getMemberScope();
             Multimap<Name, DeclarationDescriptor> simpleNameDescriptors = packageFragment.getMemberScope().getDeclaredDescriptorsAccessibleBySimpleName();
@@ -357,16 +366,7 @@ public class DeclarationResolver {
             Collection<JetFile> files = trace.get(BindingContext.PACKAGE_TO_FILES, aPackage.getFqName());
 
             if (files == null) {
-                // TODO: uncomment this after built-ins are fully rewritten to Kotlin
-                // At the moment, there are Java classes for ranges (e.g. IntRange.java) which contain static members. If someone tries to
-                // rewrite IntRange to Kotlin, this exception will be thrown because there are both class (from the Kotlin sources) and
-                // package (from static members of Java class present in kotlin-runtime.jar) for FQ name "jet.IntRange", but no sources
-                // correspond to the package.
-                // Will be safe to uncomment once there are no Java classes duplicating sources of Kotlin built-ins
-
-                // throw new IllegalStateException("declarations corresponding to " + aPackage + " are not found");
-
-                return Collections.emptySet();
+                throw new IllegalStateException("declarations corresponding to " + aPackage + " are not found");
             }
 
             declarations = Collections2.transform(files, new Function<JetFile, PsiElement>() {