diff --git a/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliLightClassGenerationSupport.java b/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliLightClassGenerationSupport.java
index c35c658b4df..bbe6a69caaa 100644
--- a/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliLightClassGenerationSupport.java
+++ b/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliLightClassGenerationSupport.java
@@ -122,7 +122,7 @@ public class CliLightClassGenerationSupport extends LightClassGenerationSupport
     @NotNull
     @Override
     public Collection<JetClassOrObject> findClassOrObjectDeclarations(@NotNull FqName fqName, @NotNull GlobalSearchScope searchScope) {
-        ClassDescriptor classDescriptor = getTrace().get(BindingContext.FQNAME_TO_CLASS_DESCRIPTOR, fqName);
+        ClassDescriptor classDescriptor = getTrace().get(BindingContext.FQNAME_TO_CLASS_DESCRIPTOR, fqName.toUnsafe());
         if (classDescriptor != null) {
             PsiElement element = BindingContextUtils.classDescriptorToDeclaration(trace.getBindingContext(), classDescriptor);
             if (element != null && PsiSearchScopeUtil.isInScope(searchScope, element)) {
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/resolver/TraceBasedJavaResolverCache.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/resolver/TraceBasedJavaResolverCache.java
index 928789c27b4..9496178235b 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/resolver/TraceBasedJavaResolverCache.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/resolver/TraceBasedJavaResolverCache.java
@@ -62,7 +62,7 @@ public class TraceBasedJavaResolverCache implements JavaResolverCache {
     @Nullable
     @Override
     public ClassDescriptor getClassResolvedFromSource(@NotNull FqName fqName) {
-        return trace.get(FQNAME_TO_CLASS_DESCRIPTOR, fqName);
+        return trace.get(FQNAME_TO_CLASS_DESCRIPTOR, fqName.toUnsafe());
     }
 
     @Nullable
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
index ef82396192c..1883328386f 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
@@ -35,6 +35,7 @@ import org.jetbrains.jet.kdoc.psi.api.KDocElement;
 import org.jetbrains.jet.lang.parsing.JetExpressionParsing;
 import org.jetbrains.jet.lang.resolve.ImportPath;
 import org.jetbrains.jet.lang.resolve.name.FqName;
+import org.jetbrains.jet.lang.resolve.name.FqNameUnsafe;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.name.SpecialNames;
 import org.jetbrains.jet.lang.types.expressions.OperatorConventions;
@@ -190,6 +191,12 @@ public class JetPsiUtil {
         return header != null ? header.getFqName() : FqName.ROOT;
     }
 
+    @Nullable
+    public static FqNameUnsafe getUnsafeFQName(@NotNull JetNamedDeclaration namedDeclaration) {
+        FqName fqName = getFQName(namedDeclaration);
+        return fqName != null ? fqName.toUnsafe() : null;
+    }
+
     @Nullable
     public static FqName getFQName(@NotNull JetNamedDeclaration namedDeclaration) {
         Name name = namedDeclaration.getNameAsName();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContext.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContext.java
index beaebe95e92..41f12bda04c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContext.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContext.java
@@ -31,6 +31,7 @@ import org.jetbrains.jet.lang.resolve.calls.inference.ConstraintSystemCompleter;
 import org.jetbrains.jet.lang.resolve.calls.model.ResolvedCall;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
 import org.jetbrains.jet.lang.resolve.name.FqName;
+import org.jetbrains.jet.lang.resolve.name.FqNameUnsafe;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 import org.jetbrains.jet.lang.types.DeferredType;
 import org.jetbrains.jet.lang.types.JetType;
@@ -245,7 +246,7 @@ public interface BindingContext {
     WritableSlice<ClassDescriptor, FunctionDescriptor> DATA_CLASS_COPY_FUNCTION =
             Slices.<ClassDescriptor, FunctionDescriptor>sliceBuilder().build();
 
-    WritableSlice<FqName, ClassDescriptor> FQNAME_TO_CLASS_DESCRIPTOR = new BasicWritableSlice<FqName, ClassDescriptor>(DO_NOTHING, true);
+    WritableSlice<FqNameUnsafe, ClassDescriptor> FQNAME_TO_CLASS_DESCRIPTOR = new BasicWritableSlice<FqNameUnsafe, ClassDescriptor>(DO_NOTHING, true);
     WritableSlice<JetFile, PackageFragmentDescriptor> FILE_TO_PACKAGE_FRAGMENT = Slices.createSimpleSlice();
     WritableSlice<FqName, Collection<JetFile>> PACKAGE_TO_FILES = Slices.createSimpleSlice();
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
index e1a59dd542b..5e676d12ac2 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
@@ -491,7 +491,7 @@ public class TypeHierarchyResolver {
                     createClassDescriptorForSingleton(declaration, JetPsiUtil.safeName(declaration.getName()), ClassKind.OBJECT);
 
             owner.addClassifierDescriptor(descriptor);
-            trace.record(FQNAME_TO_CLASS_DESCRIPTOR, JetPsiUtil.getFQName(declaration), descriptor);
+            trace.record(FQNAME_TO_CLASS_DESCRIPTOR, JetPsiUtil.getUnsafeFQName(declaration), descriptor);
 
             descriptor.getBuilder().setClassObjectDescriptor(createSyntheticClassObject(descriptor));
         }
@@ -572,7 +572,7 @@ public class TypeHierarchyResolver {
             MutableClassDescriptor mutableClassDescriptor = new MutableClassDescriptor(
                     containingDeclaration, outerScope, kind, isInner, JetPsiUtil.safeName(klass.getName()));
             context.getClasses().put(klass, mutableClassDescriptor);
-            trace.record(FQNAME_TO_CLASS_DESCRIPTOR, JetPsiUtil.getFQName(klass), mutableClassDescriptor);
+            trace.record(FQNAME_TO_CLASS_DESCRIPTOR, JetPsiUtil.getUnsafeFQName(klass), mutableClassDescriptor);
 
             createClassObjectForEnumClass(mutableClassDescriptor);
 
diff --git a/idea/src/org/jetbrains/jet/plugin/references/BuiltInsReferenceResolver.java b/idea/src/org/jetbrains/jet/plugin/references/BuiltInsReferenceResolver.java
index 6fc75497552..cf72cca91a8 100644
--- a/idea/src/org/jetbrains/jet/plugin/references/BuiltInsReferenceResolver.java
+++ b/idea/src/org/jetbrains/jet/plugin/references/BuiltInsReferenceResolver.java
@@ -138,7 +138,7 @@ public class BuiltInsReferenceResolver extends AbstractProjectComponent {
             return ((ClassDescriptor) currentParent).getClassObjectDescriptor();
         }
         else {
-            return bindingContext.get(BindingContext.FQNAME_TO_CLASS_DESCRIPTOR, DescriptorUtils.getFqNameSafe(originalDescriptor));
+            return bindingContext.get(BindingContext.FQNAME_TO_CLASS_DESCRIPTOR, DescriptorUtils.getFqName(originalDescriptor));
         }
     }
 
diff --git a/idea/tests/org/jetbrains/jet/plugin/refactoring/rename/AbstractRenameTest.kt b/idea/tests/org/jetbrains/jet/plugin/refactoring/rename/AbstractRenameTest.kt
index 6a517b448c6..5a38ef2aff9 100644
--- a/idea/tests/org/jetbrains/jet/plugin/refactoring/rename/AbstractRenameTest.kt
+++ b/idea/tests/org/jetbrains/jet/plugin/refactoring/rename/AbstractRenameTest.kt
@@ -43,6 +43,7 @@ import org.jetbrains.jet.lang.resolve.name.Name
 import org.jetbrains.jet.lang.resolve.BindingContextUtils
 import org.jetbrains.jet.lang.descriptors.ClassDescriptor
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor
+import org.jetbrains.jet.lang.resolve.name.FqNameUnsafe
 
 private enum class RenameType {
     JAVA_CLASS
@@ -167,7 +168,7 @@ public abstract class AbstractRenameTest : MultiFileTestCase() {
     private fun doRenameInKotlinClass(renameParamsObject: JsonObject, context: TestContext,
                                       findDescriptorToRename: (ClassDescriptor) -> DeclarationDescriptor
     ) {
-        val classFqName = FqName(renameParamsObject.getString("classFQN"))
+        val classFqName = FqNameUnsafe(renameParamsObject.getString("classFQN"))
         val newName = renameParamsObject.getString("newName")
         val mainFilePath = renameParamsObject.getNullableString("mainFile") ?: "${getTestDirName(false)}.kt"