diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ClassBuilderOnDemand.java b/compiler/backend/src/org/jetbrains/jet/codegen/ClassBuilderOnDemand.java
index c99c82831b2..87a1f1c3adb 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ClassBuilderOnDemand.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ClassBuilderOnDemand.java
@@ -16,49 +16,30 @@
 
 package org.jetbrains.jet.codegen;
 
-import com.google.common.collect.Lists;
+import kotlin.Function0;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.storage.LockBasedStorageManager;
+import org.jetbrains.jet.storage.NotNullLazyValue;
 
-import java.util.List;
+public class ClassBuilderOnDemand {
+    private final NotNullLazyValue<ClassBuilder> classBuilder;
 
-public abstract class ClassBuilderOnDemand {
-
-    private ClassBuilder classBuilder;
-
-    private final List<ClassBuilderCallback> optionalDeclarations = Lists.newArrayList();
-
-    interface ClassBuilderCallback {
-        void doSomething(@NotNull ClassBuilder classBuilder);
-    }
-
-    @NotNull
-    protected abstract ClassBuilder createClassBuilder();
-
-    public void addOptionalDeclaration(@NotNull ClassBuilderCallback callback) {
-        optionalDeclarations.add(callback);
-        if (classBuilder != null) {
-            callback.doSomething(classBuilder);
-        }
+    public ClassBuilderOnDemand(@NotNull Function0<ClassBuilder> createClassBuilder) {
+        this.classBuilder = LockBasedStorageManager.NO_LOCKS.createLazyValue(createClassBuilder);
     }
 
     @NotNull
     public ClassBuilder getClassBuilder() {
-        if (classBuilder == null) {
-            classBuilder = createClassBuilder();
-            for (ClassBuilderCallback callback : optionalDeclarations) {
-                callback.doSomething(classBuilder);
-            }
-        }
-        return classBuilder;
+        return classBuilder.invoke();
     }
 
     public void done() {
-        if (classBuilder != null) {
-            classBuilder.done();
+        if (isActivated()) {
+            classBuilder.invoke().done();
         }
     }
 
     public boolean isActivated() {
-        return classBuilder != null;
+        return classBuilder.isComputed();
     }
 }
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ClassFileFactory.java b/compiler/backend/src/org/jetbrains/jet/codegen/ClassFileFactory.java
index a8b6204022e..a750e241b61 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ClassFileFactory.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ClassFileFactory.java
@@ -35,9 +35,6 @@ import org.jetbrains.org.objectweb.asm.Type;
 import java.io.File;
 import java.util.*;
 
-import static org.jetbrains.jet.codegen.AsmUtil.asmTypeByFqNameWithoutInnerClasses;
-import static org.jetbrains.jet.lang.resolve.java.PackageClassUtils.getPackageClassFqName;
-
 public class ClassFileFactory implements OutputFileCollection {
     private final GenerationState state;
     private final ClassBuilderFactory builderFactory;
@@ -57,7 +54,7 @@ public class ClassFileFactory implements OutputFileCollection {
     }
 
     @NotNull
-    private ClassBuilder newVisitor(@NotNull Type asmType, @NotNull Collection<? extends PsiFile> sourceFiles) {
+    public ClassBuilder newVisitor(@NotNull Type asmType, @NotNull Collection<? extends PsiFile> sourceFiles) {
         String outputFilePath = asmType.getInternalName() + ".class";
         state.getProgress().reportOutput(toIoFilesIgnoringNonPhysical(sourceFiles), new File(outputFilePath));
         ClassBuilder answer = builderFactory.newClassBuilder();
@@ -106,18 +103,11 @@ public class ClassFileFactory implements OutputFileCollection {
     }
 
     @NotNull
-    public PackageCodegen forPackage(@NotNull final FqName fqName, @NotNull final Collection<JetFile> files) {
+    public PackageCodegen forPackage(@NotNull FqName fqName, @NotNull Collection<JetFile> files) {
         assert !isDone : "Already done!";
         PackageCodegen codegen = package2codegen.get(fqName);
         if (codegen == null) {
-            ClassBuilderOnDemand onDemand = new ClassBuilderOnDemand() {
-                @NotNull
-                @Override
-                protected ClassBuilder createClassBuilder() {
-                    return newVisitor(asmTypeByFqNameWithoutInnerClasses(getPackageClassFqName(fqName)), files);
-                }
-            };
-            codegen = new PackageCodegen(onDemand, fqName, state, files);
+            codegen = new PackageCodegen(state, files, fqName);
             package2codegen.put(fqName, codegen);
         }
 
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/PackageCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/PackageCodegen.java
index 174ea3a6c4e..4fec035d0d0 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/PackageCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/PackageCodegen.java
@@ -22,10 +22,10 @@ import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.progress.ProcessCanceledException;
 import com.intellij.openapi.util.io.FileUtil;
 import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.psi.PsiFile;
 import com.intellij.util.ArrayUtil;
 import com.intellij.util.PathUtil;
 import com.intellij.util.SmartList;
+import kotlin.Function0;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.codegen.context.CodegenContext;
@@ -74,28 +74,27 @@ public class PackageCodegen {
     private final Collection<JetFile> files;
     private final PackageFragmentDescriptor packageFragment;
     private final PackageFragmentDescriptor compiledPackageFragment;
+    private final List<DeserializedCallableMemberDescriptor> previouslyCompiledCallables;
 
-    public PackageCodegen(
-            @NotNull ClassBuilderOnDemand v,
-            @NotNull final FqName fqName,
-            @NotNull GenerationState state,
-            @NotNull Collection<JetFile> packageFiles
-    ) {
+    public PackageCodegen(@NotNull GenerationState state, @NotNull Collection<JetFile> files, @NotNull final FqName fqName) {
         this.state = state;
-        this.v = v;
-        this.files = packageFiles;
+        this.files = files;
         this.packageFragment = getOnlyPackageFragment();
-        this.compiledPackageFragment = getCompiledPackageFragment();
+        this.compiledPackageFragment = getCompiledPackageFragment(packageFragment);
+        this.previouslyCompiledCallables = filterDeserializedCallables(compiledPackageFragment);
 
-        final PsiFile sourceFile = packageFiles.size() == 1 && getPreviouslyCompiledCallables().isEmpty()
-                                   ? packageFiles.iterator().next().getContainingFile() : null;
-
-        v.addOptionalDeclaration(new ClassBuilderOnDemand.ClassBuilderCallback() {
+        this.v = new ClassBuilderOnDemand(new Function0<ClassBuilder>() {
             @Override
-            public void doSomething(@NotNull ClassBuilder v) {
+            public ClassBuilder invoke() {
+                Collection<JetFile> files = PackageCodegen.this.files;
+                JetFile sourceFile = files.size() == 1 && previouslyCompiledCallables.isEmpty()
+                                     ? files.iterator().next() : null;
+
+                String className = JvmClassName.byFqNameWithoutInnerClasses(getPackageClassFqName(fqName)).getInternalName();
+                ClassBuilder v = PackageCodegen.this.state.getFactory().newVisitor(Type.getObjectType(className), files);
                 v.defineClass(sourceFile, V1_6,
                               ACC_PUBLIC | ACC_FINAL,
-                              JvmClassName.byFqNameWithoutInnerClasses(getPackageClassFqName(fqName)).getInternalName(),
+                              className,
                               null,
                               "java/lang/Object",
                               ArrayUtil.EMPTY_STRING_ARRAY
@@ -104,12 +103,13 @@ public class PackageCodegen {
                 if (sourceFile != null) {
                     v.visitSource(sourceFile.getName(), null);
                 }
+                return v;
             }
         });
     }
 
     @Nullable
-    private PackageFragmentDescriptor getCompiledPackageFragment() {
+    private static PackageFragmentDescriptor getCompiledPackageFragment(@NotNull PackageFragmentDescriptor packageFragment) {
         if (!IncrementalCompilation.ENABLED) {
             return null;
         }
@@ -125,20 +125,21 @@ public class PackageCodegen {
     }
 
     @NotNull
-    private List<DeserializedCallableMemberDescriptor> getPreviouslyCompiledCallables() {
+    private static List<DeserializedCallableMemberDescriptor> filterDeserializedCallables(@Nullable PackageFragmentDescriptor packageFragment) {
+        if (packageFragment == null) {
+            return Collections.emptyList();
+        }
         List<DeserializedCallableMemberDescriptor> callables = Lists.newArrayList();
-        if (compiledPackageFragment != null) {
-            for (DeclarationDescriptor member : compiledPackageFragment.getMemberScope().getAllDescriptors()) {
-                if (member instanceof DeserializedCallableMemberDescriptor) {
-                    callables.add((DeserializedCallableMemberDescriptor) member);
-                }
+        for (DeclarationDescriptor member : packageFragment.getMemberScope().getAllDescriptors()) {
+            if (member instanceof DeserializedCallableMemberDescriptor) {
+                callables.add((DeserializedCallableMemberDescriptor) member);
             }
         }
         return callables;
     }
 
-    private void generateDelegationsToPreviouslyCompiled(Map<CallableMemberDescriptor, Runnable> generateCallableMemberTasks) {
-        for (final DeserializedCallableMemberDescriptor member : getPreviouslyCompiledCallables()) {
+    private void generateDelegationsToPreviouslyCompiled(@NotNull Map<CallableMemberDescriptor, Runnable> generateCallableMemberTasks) {
+        for (final DeserializedCallableMemberDescriptor member : previouslyCompiledCallables) {
             generateCallableMemberTasks.put(member, new Runnable() {
                 @Override
                 public void run() {