diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/descriptors/AbstractLazyMemberScope.kt b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/descriptors/AbstractLazyMemberScope.kt
index 018a68eb931..1e49f87c8db 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/descriptors/AbstractLazyMemberScope.kt
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/descriptors/AbstractLazyMemberScope.kt
@@ -53,7 +53,7 @@ public abstract class AbstractLazyMemberScope<D : DeclarationDescriptor, DP : De
                 LazyScriptClassDescriptor(resolveSession, thisDescriptor, name, it)
             else
                 LazyClassDescriptor(resolveSession, thisDescriptor, name, it)
-        }
+        }.toReadOnlyList()
     }
 
     override fun getContainingDeclaration() = thisDescriptor
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.kt b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.kt
index ea4ebaadeee..a1f4e98cdd3 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.kt
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.kt
@@ -23,6 +23,7 @@ import org.jetbrains.jet.lang.types.checker.JetTypeChecker
 import org.jetbrains.jet.utils.Printer
 
 import java.util.*
+import com.intellij.util.SmartList
 
 // Reads from:
 // 1. Maps
@@ -37,7 +38,7 @@ public class WritableScopeImpl(scope: JetScope,
                                debugName: String)
 : WritableScopeWithImports(scope, redeclarationHandler, debugName) {
 
-    private val explicitlyAddedDescriptors = ArrayList<DeclarationDescriptor>()
+    private val explicitlyAddedDescriptors = SmartList<DeclarationDescriptor>()
     private val declaredDescriptorsAccessibleBySimpleName = HashMultimap.create<Name, DeclarationDescriptor>()
 
     private var functionGroups: SetMultimap<Name, FunctionDescriptor>? = null