diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java
index 30d98d468cd..6b46dd13c2e 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java
@@ -220,7 +220,7 @@ public class IntrinsicMethods {
 
     private void declareIntrinsicProperty(Name className, Name methodName, IntrinsicMethod implementation) {
         final JetScope numberScope = getClassMemberScope(className);
-        Set<VariableDescriptor> properties = numberScope.getProperties(methodName);
+        Collection<VariableDescriptor> properties = numberScope.getProperties(methodName);
         assert properties.size() == 1;
         final VariableDescriptor property = properties.iterator().next();
         myMethods.put(property.getOriginal(), implementation);
@@ -228,7 +228,7 @@ public class IntrinsicMethods {
 
     private void declareIntrinsicFunction(Name className, Name functionName, int arity, IntrinsicMethod implementation, boolean original) {
         JetScope memberScope = getClassMemberScope(className);
-        final Set<FunctionDescriptor> group = memberScope.getFunctions(functionName);
+        final Collection<FunctionDescriptor> group = memberScope.getFunctions(functionName);
         for (FunctionDescriptor descriptor : group) {
             if (className.equals(descriptor.getContainingDeclaration().getName()) && descriptor.getValueParameters().size() == arity) {
                 myMethods.put(original ? descriptor.getOriginal() : descriptor, implementation);
@@ -236,7 +236,7 @@ public class IntrinsicMethods {
         }
     }
 
-    private void declareOverload(Set<FunctionDescriptor> group, int arity, IntrinsicMethod implementation) {
+    private void declareOverload(Collection<FunctionDescriptor> group, int arity, IntrinsicMethod implementation) {
         for (FunctionDescriptor descriptor : group) {
             if (descriptor.getValueParameters().size() == arity) {
                 myMethods.put(descriptor.getOriginal(), implementation);
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaClassOrPackageScope.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaClassOrPackageScope.java
index 928ff13c239..9d5d8a013e5 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaClassOrPackageScope.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaClassOrPackageScope.java
@@ -57,13 +57,13 @@ public abstract class JavaClassOrPackageScope extends JetScopeImpl {
 
     @NotNull
     @Override
-    public Set<VariableDescriptor> getProperties(@NotNull Name name) {
+    public Collection<VariableDescriptor> getProperties(@NotNull Name name) {
         return semanticServices.getDescriptorResolver().resolveFieldGroupByName(name, resolverScopeData);
     }
 
     @NotNull
     @Override
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         return semanticServices.getDescriptorResolver().resolveFunctionGroup(name, resolverScopeData);
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/WhenChecker.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/WhenChecker.java
index 563d4389c37..23edeacc6d3 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/WhenChecker.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/WhenChecker.java
@@ -27,6 +27,7 @@ import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.TypeProjection;
 
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Set;
 
@@ -46,7 +47,7 @@ public class WhenChecker {
         ClassDescriptor classObjectDescriptor = classDescriptor.getClassObjectDescriptor();
         assert classObjectDescriptor != null;
         JetScope memberScope = classObjectDescriptor.getMemberScope(Collections.<TypeProjection>emptyList());
-        Set<ClassDescriptor> objectDescriptors = memberScope.getObjectDescriptors();
+        Collection<ClassDescriptor> objectDescriptors = memberScope.getObjectDescriptors();
         boolean isExhaust = true;
         boolean notEmpty = false;
         for (ClassDescriptor descriptor : objectDescriptors) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorUtil.java b/compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorUtil.java
index 13947a18c05..4caafc8ad3d 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorUtil.java
@@ -142,7 +142,7 @@ public class FunctionDescriptorUtil {
 
         ClassifierDescriptor classDescriptorForFunction = functionType.getConstructor().getDeclarationDescriptor();
         assert classDescriptorForFunction instanceof ClassDescriptor;
-        Set<FunctionDescriptor> invokeFunctions = ((ClassDescriptor) classDescriptorForFunction).getMemberScope(functionType.getArguments()).getFunctions(Name.identifier("invoke"));
+        Collection<FunctionDescriptor> invokeFunctions = ((ClassDescriptor) classDescriptorForFunction).getMemberScope(functionType.getArguments()).getFunctions(Name.identifier("invoke"));
         assert invokeFunctions.size() == 1;
         return invokeFunctions.iterator().next();
     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/AbstractScopeAdapter.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/AbstractScopeAdapter.java
index 959b6628983..97fc0e2cdca 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/AbstractScopeAdapter.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/AbstractScopeAdapter.java
@@ -49,7 +49,7 @@ public abstract class AbstractScopeAdapter implements JetScope {
 
     @NotNull
     @Override
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         return getWorkerScope().getFunctions(name);
     }
 
@@ -70,13 +70,13 @@ public abstract class AbstractScopeAdapter implements JetScope {
 
     @NotNull
     @Override
-    public Set<ClassDescriptor> getObjectDescriptors() {
+    public Collection<ClassDescriptor> getObjectDescriptors() {
         return getWorkerScope().getObjectDescriptors();
     }
 
     @NotNull
     @Override
-    public Set<VariableDescriptor> getProperties(@NotNull Name name) {
+    public Collection<VariableDescriptor> getProperties(@NotNull Name name) {
         return getWorkerScope().getProperties(name);
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorUtils.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorUtils.java
index c7045cf69f7..e5b2cf787f2 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorUtils.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorUtils.java
@@ -31,6 +31,7 @@ import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
 import org.jetbrains.jet.lang.types.*;
 import org.jetbrains.jet.lang.types.lang.JetStandardClasses;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -206,7 +207,7 @@ public class DescriptorUtils {
     }
 
     @Nullable
-    public static VariableDescriptor filterNonExtensionProperty(Set<VariableDescriptor> variables) {
+    public static VariableDescriptor filterNonExtensionProperty(Collection<VariableDescriptor> variables) {
         for (VariableDescriptor variable : variables) {
             if (!variable.getReceiverParameter().exists()) {
                 return variable;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
index 44c7e30fcf6..6cda23778e9 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java
@@ -164,7 +164,7 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
 
     @NotNull
     @Override
-    public Set<ClassDescriptor> getObjectDescriptors() {
+    public Collection<ClassDescriptor> getObjectDescriptors() {
         throw new UnsupportedOperationException(); // TODO
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScope.java
index 5f313148267..07eec60d39e 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScope.java
@@ -51,19 +51,19 @@ public interface JetScope {
     ClassDescriptor getObjectDescriptor(@NotNull Name name);
 
     @NotNull
-    Set<ClassDescriptor> getObjectDescriptors();
+    Collection<ClassDescriptor> getObjectDescriptors();
 
     @Nullable
     NamespaceDescriptor getNamespace(@NotNull Name name);
 
     @NotNull
-    Set<VariableDescriptor> getProperties(@NotNull Name name);
+    Collection<VariableDescriptor> getProperties(@NotNull Name name);
 
     @Nullable
     VariableDescriptor getLocalVariable(@NotNull Name name);
 
     @NotNull
-    Set<FunctionDescriptor> getFunctions(@NotNull Name name);
+    Collection<FunctionDescriptor> getFunctions(@NotNull Name name);
 
     @NotNull
     DeclarationDescriptor getContainingDeclaration();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScopeImpl.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScopeImpl.java
index fcf8f556625..eb37ce906e7 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScopeImpl.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/JetScopeImpl.java
@@ -49,7 +49,7 @@ public abstract class JetScopeImpl implements JetScope {
 
     @NotNull
     @Override
-    public Set<VariableDescriptor> getProperties(@NotNull Name name) {
+    public Collection<VariableDescriptor> getProperties(@NotNull Name name) {
         return Collections.emptySet();
     }
 
@@ -71,7 +71,7 @@ public abstract class JetScopeImpl implements JetScope {
 
     @NotNull
     @Override
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         return Collections.emptySet();
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/SubstitutingScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/SubstitutingScope.java
index 6806c9632ba..e42273defa3 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/SubstitutingScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/SubstitutingScope.java
@@ -66,7 +66,7 @@ public class SubstitutingScope implements JetScope {
     }
 
     @NotNull
-    private <D extends DeclarationDescriptor> Set<D> substitute(@NotNull Set<D> descriptors) {
+    private <D extends DeclarationDescriptor> Collection<D> substitute(@NotNull Collection<D> descriptors) {
         if (substitutor.isEmpty()) return descriptors;
         if (descriptors.isEmpty()) return descriptors;
 
@@ -83,7 +83,7 @@ public class SubstitutingScope implements JetScope {
 
     @NotNull
     @Override
-    public Set<VariableDescriptor> getProperties(@NotNull Name name) {
+    public Collection<VariableDescriptor> getProperties(@NotNull Name name) {
         return substitute(workerScope.getProperties(name));
     }
 
@@ -104,13 +104,13 @@ public class SubstitutingScope implements JetScope {
 
     @NotNull
     @Override
-    public Set<ClassDescriptor> getObjectDescriptors() {
+    public Collection<ClassDescriptor> getObjectDescriptors() {
         return substitute(workerScope.getObjectDescriptors());
     }
 
     @NotNull
     @Override
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         return substitute(workerScope.getFunctions(name));
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.java
index 58496eb4e4a..4bc59570f26 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.java
@@ -290,7 +290,7 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     @NotNull
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         checkMayRead();
 
         Set<FunctionDescriptor> result = Sets.newLinkedHashSet(getFunctionGroups().get(name));
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeWithImports.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeWithImports.java
index 4711cb84195..043d502f1c0 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeWithImports.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeWithImports.java
@@ -24,6 +24,7 @@ import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
@@ -145,7 +146,7 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @NotNull
     @Override
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         checkMayRead();
 
         if (getImports().isEmpty()) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WriteThroughScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WriteThroughScope.java
index 136dbf78dc5..1528dd3f0c8 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WriteThroughScope.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WriteThroughScope.java
@@ -76,7 +76,7 @@ public class WriteThroughScope extends WritableScopeWithImports {
 
     @Override
     @NotNull
-    public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+    public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
         checkMayRead();
 
         Set<FunctionDescriptor> result = Sets.newLinkedHashSet();
diff --git a/compiler/tests/org/jetbrains/jet/jvm/compiler/JavaDescriptorResolverTest.java b/compiler/tests/org/jetbrains/jet/jvm/compiler/JavaDescriptorResolverTest.java
index 999913aa8fc..cd44e7d0798 100644
--- a/compiler/tests/org/jetbrains/jet/jvm/compiler/JavaDescriptorResolverTest.java
+++ b/compiler/tests/org/jetbrains/jet/jvm/compiler/JavaDescriptorResolverTest.java
@@ -35,6 +35,7 @@ import org.junit.Assert;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Collection;
 import java.util.Set;
 
 /**
@@ -53,7 +54,7 @@ public class JavaDescriptorResolverTest extends TestCaseWithTmpdir {
     public void testStaticFinal() throws Exception {
         JavaDescriptorResolver javaDescriptorResolver = compileFileGetJavaDescriptorResolver("staticFinal.java");
         NamespaceDescriptor ns = javaDescriptorResolver.resolveNamespace(new FqName("StaticFinal"), DescriptorSearchRule.ERROR_IF_FOUND_IN_KOTLIN);
-        Set<VariableDescriptor> foos = ns.getMemberScope().getProperties(Name.identifier("foo"));
+        Collection<VariableDescriptor> foos = ns.getMemberScope().getProperties(Name.identifier("foo"));
         Assert.assertEquals(1, foos.size());
         VariableDescriptor foo = foos.iterator().next();
         Assert.assertFalse(foo.getType().isNullable());
diff --git a/compiler/tests/org/jetbrains/jet/jvm/compiler/NamespaceComparator.java b/compiler/tests/org/jetbrains/jet/jvm/compiler/NamespaceComparator.java
index 1106bcf906d..b5bcbb81953 100644
--- a/compiler/tests/org/jetbrains/jet/jvm/compiler/NamespaceComparator.java
+++ b/compiler/tests/org/jetbrains/jet/jvm/compiler/NamespaceComparator.java
@@ -144,8 +144,8 @@ public class NamespaceComparator {
         }
 
         for (Name name : sorted(propertyNames)) {
-            Set<VariableDescriptor> pa = nsa.getMemberScope().getProperties(name);
-            Set<VariableDescriptor> pb = nsb.getMemberScope().getProperties(name);
+            Collection<VariableDescriptor> pa = nsa.getMemberScope().getProperties(name);
+            Collection<VariableDescriptor> pb = nsb.getMemberScope().getProperties(name);
             compareDeclarationSets("Properties in package " + nsa, pa, pb, sb);
 
             Assert.assertTrue(nsb.getMemberScope().getFunctions(Name.identifier(PropertyCodegen.getterName(name))).isEmpty());
@@ -153,8 +153,8 @@ public class NamespaceComparator {
         }
 
         for (Name name : sorted(functionNames)) {
-            Set<FunctionDescriptor> fa = nsa.getMemberScope().getFunctions(name);
-            Set<FunctionDescriptor> fb = nsb.getMemberScope().getFunctions(name);
+            Collection<FunctionDescriptor> fa = nsa.getMemberScope().getFunctions(name);
+            Collection<FunctionDescriptor> fb = nsb.getMemberScope().getFunctions(name);
             compareDeclarationSets("Functions in package " + nsa, fa, fb, sb);
         }
 
@@ -162,8 +162,8 @@ public class NamespaceComparator {
     }
 
     private static void compareDeclarationSets(String message,
-            Set<? extends DeclarationDescriptor> a,
-            Set<? extends DeclarationDescriptor> b,
+            Collection<? extends DeclarationDescriptor> a,
+            Collection<? extends DeclarationDescriptor> b,
             @NotNull StringBuilder sb) {
         String at = serializedDeclarationSets(a);
         String bt = serializedDeclarationSets(b);
diff --git a/compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java b/compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java
index a13b9cdc044..dc376d30df3 100644
--- a/compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java
+++ b/compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java
@@ -672,7 +672,7 @@ public class JetTypeCheckerTest extends JetLiteFixture {
 
             @NotNull
             @Override
-            public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
+            public Collection<FunctionDescriptor> getFunctions(@NotNull Name name) {
                 Set<FunctionDescriptor> writableFunctionGroup = Sets.newLinkedHashSet();
                 for (String funDecl : FUNCTION_DECLARATIONS) {
                     FunctionDescriptor functionDescriptor = descriptorResolver.resolveFunctionDescriptor(this.getContainingDeclaration(), this, JetPsiFactory.createFunction(getProject(), funDecl), JetTestUtils.DUMMY_TRACE);
diff --git a/idea/src/org/jetbrains/jet/plugin/libraries/JetSourceNavigationHelper.java b/idea/src/org/jetbrains/jet/plugin/libraries/JetSourceNavigationHelper.java
index f34ac402af9..51cd84423f8 100644
--- a/idea/src/org/jetbrains/jet/plugin/libraries/JetSourceNavigationHelper.java
+++ b/idea/src/org/jetbrains/jet/plugin/libraries/JetSourceNavigationHelper.java
@@ -50,6 +50,7 @@ import org.jetbrains.jet.resolve.DescriptorRenderer;
 import org.jetbrains.jet.util.slicedmap.ReadOnlySlice;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
@@ -233,7 +234,7 @@ public class JetSourceNavigationHelper {
             }
 
             @Override
-            public Set<VariableDescriptor> getCandidatesFromScope(JetScope scope, Name name) {
+            public Collection<VariableDescriptor> getCandidatesFromScope(JetScope scope, Name name) {
                 return scope.getProperties(name);
             }
         });
@@ -275,7 +276,7 @@ public class JetSourceNavigationHelper {
             }
 
             @Override
-            public Set<FunctionDescriptor> getCandidatesFromScope(JetScope scope, Name name) {
+            public Collection<FunctionDescriptor> getCandidatesFromScope(JetScope scope, Name name) {
                 return scope.getFunctions(name);
             }
         });
@@ -284,6 +285,6 @@ public class JetSourceNavigationHelper {
     private interface Matcher<Decl extends JetDeclaration, Descr extends CallableDescriptor> {
         boolean areSame(Decl declaration, Descr descriptor);
 
-        Set<Descr> getCandidatesFromScope(JetScope scope, Name name);
+        Collection<Descr> getCandidatesFromScope(JetScope scope, Name name);
     }
 }
diff --git a/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsDescriptorUtils.java b/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsDescriptorUtils.java
index f47dfd15b85..59860ed1ea6 100644
--- a/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsDescriptorUtils.java
+++ b/js/js.translator/src/org/jetbrains/k2js/translate/utils/JsDescriptorUtils.java
@@ -66,7 +66,7 @@ public final class JsDescriptorUtils {
     @NotNull
     public static FunctionDescriptor getFunctionByName(@NotNull JetScope scope,
                                                        @NotNull Name name) {
-        Set<FunctionDescriptor> functionDescriptors = scope.getFunctions(name);
+        Collection<FunctionDescriptor> functionDescriptors = scope.getFunctions(name);
         assert functionDescriptors.size() == 1 :
             "In scope " + scope + " supposed to be exactly one " + name + " function.\n" +
             "Found: " + functionDescriptors.size();
@@ -83,7 +83,7 @@ public final class JsDescriptorUtils {
     @NotNull
     public static PropertyDescriptor getPropertyByName(@NotNull JetScope scope,
                                                        @NotNull Name name) {
-        Set<VariableDescriptor> variables = scope.getProperties(name);
+        Collection<VariableDescriptor> variables = scope.getProperties(name);
         assert variables.size() == 1 : "Actual size: " + variables.size();
         VariableDescriptor variable = variables.iterator().next();
         PropertyDescriptor descriptor = (PropertyDescriptor)variable;