diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd565c7..d5d8485 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
+## 0.4.2+1
+
+* Contains a fix for the `useSharedSources` option that could result in null
+  library elements when running on multiple entry points.
+
 ## 0.4.2
 
 * Use Strong Mode, fixes
-  [#38](https://github.com/dart-lang/code_transformers/issues/38). 
+  [#38](https://github.com/dart-lang/code_transformers/issues/38).
 
 ## 0.4.1
 
diff --git a/lib/src/resolver_impl.dart b/lib/src/resolver_impl.dart
index efc5cfd..699f3eb 100644
--- a/lib/src/resolver_impl.dart
+++ b/lib/src/resolver_impl.dart
@@ -49,11 +49,15 @@ class ResolverImpl implements Resolver {
   /// Completer for wrapping up the current phase.
   Completer _currentPhaseComplete;
 
+  /// Whether or not we are using a shared sources cache.
+  final bool _usingSharedSources;
+
   /// Creates a resolver with a given [sdk] implementation for resolving
   /// `dart:*` imports.
   ResolverImpl(DartSdk sdk, DartUriResolver dartUriResolver,
       {AnalysisOptions options, Map<AssetId, AssetBasedSource> sources})
-      : sources = sources ?? <AssetId, AssetBasedSource>{} {
+      : _usingSharedSources = sources != null,
+        sources = sources ?? <AssetId, AssetBasedSource>{} {
     if (options == null) {
       options = new AnalysisOptionsImpl()
         ..cacheSize = 256 // # of sources to cache ASTs for.
@@ -144,12 +148,17 @@ class ResolverImpl implements Resolver {
     return visiting.future.then((_) {
       var changeSet = new ChangeSet();
       toUpdate.forEach((pending) => pending.apply(changeSet));
-      var unreachableAssets =
-          sources.keys.toSet().difference(visited).map((id) => sources[id]);
-      for (var unreachable in unreachableAssets) {
-        changeSet.removedSource(unreachable);
-        unreachable.updateContents(null);
-        sources.remove(unreachable.assetId);
+
+      // If we aren't using shared sources, then remove from the cache any
+      // sources which are no longer reachable.
+      if (!_usingSharedSources) {
+        var unreachableAssets =
+            sources.keys.toSet().difference(visited).map((id) => sources[id]);
+        for (var unreachable in unreachableAssets) {
+          changeSet.removedSource(unreachable);
+          unreachable.updateContents(null);
+          sources.remove(unreachable.assetId);
+        }
       }
 
       // Update the analyzer context with the latest sources
diff --git a/pubspec.yaml b/pubspec.yaml
index 9053f9a..2b03081 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: code_transformers
-version: 0.4.2
+version: 0.4.2+1
 author: Dart Team <misc@dartlang.org>
 description: Collection of utilities related to creating barback transformers.
 homepage: https://github.com/dart-lang/code-transformers