diff --git a/apps/opencs/model/doc/savingstages.cpp b/apps/opencs/model/doc/savingstages.cpp
index ee65248e2f..82a965ae40 100644
--- a/apps/opencs/model/doc/savingstages.cpp
+++ b/apps/opencs/model/doc/savingstages.cpp
@@ -321,6 +321,10 @@ void CSMDoc::WriteCellCollectionStage::perform (int stage, Messages& messages)
                 {
                     CSMWorld::CellRef refRecord = ref.get();
 
+                    // Check for uninitialized content file
+                    if (!refRecord.mRefNum.hasContentFile())
+                        refRecord.mRefNum.mContentFile = 0;
+
                     // recalculate the ref's cell location
                     std::ostringstream stream;
                     if (!interior)
diff --git a/apps/opencs/model/world/data.cpp b/apps/opencs/model/world/data.cpp
index 8b0a9b384d..1cc4a2cbf4 100644
--- a/apps/opencs/model/world/data.cpp
+++ b/apps/opencs/model/world/data.cpp
@@ -64,7 +64,7 @@ int CSMWorld::Data::count (RecordBase::State state, const CollectionBase& collec
 CSMWorld::Data::Data (ToUTF8::FromType encoding, const ResourcesManager& resourcesManager, const Fallback::Map* fallback, const boost::filesystem::path& resDir)
 : mEncoder (encoding), mPathgrids (mCells), mRefs (mCells),
   mResourcesManager (resourcesManager), mFallbackMap(fallback),
-  mReader (0), mDialogue (0), mReaderIndex(0), mResourceSystem(new Resource::ResourceSystem(resourcesManager.getVFS()))
+  mReader (0), mDialogue (0), mReaderIndex(1), mResourceSystem(new Resource::ResourceSystem(resourcesManager.getVFS()))
 {
     mResourceSystem->getSceneManager()->setShaderPath((resDir / "shaders").string());
 
@@ -899,9 +899,11 @@ int CSMWorld::Data::startLoading (const boost::filesystem::path& path, bool base
 
     mReader = new ESM::ESMReader;
     mReader->setEncoder (&mEncoder);
-    mReader->setIndex(mReaderIndex++);
+    mReader->setIndex((project || !base) ? 0 : mReaderIndex++);
     mReader->open (path.string());
 
+    mContentFileNames.insert(std::make_pair(path.filename().string(), mReader->getIndex()));
+
     mBase = base;
     mProject = project;
 
@@ -914,6 +916,20 @@ int CSMWorld::Data::startLoading (const boost::filesystem::path& path, bool base
         mMetaData.setRecord (0, Record<MetaData> (RecordBase::State_ModifiedOnly, 0, &metaData));
     }
 
+    // Fix uninitialized master data index
+    for (std::vector<ESM::Header::MasterData>::const_iterator masterData = mReader->getGameFiles().begin();
+        masterData != mReader->getGameFiles().end(); ++masterData)
+    {
+        std::map<std::string, int>::iterator nameResult = mContentFileNames.find(masterData->name);
+        if (nameResult != mContentFileNames.end())
+        {
+            ESM::Header::MasterData& hackedMasterData = const_cast<ESM::Header::MasterData&>(*masterData);
+
+
+            hackedMasterData.index = nameResult->second;
+        }
+    }
+
     return mReader->getRecordCount();
 }
 
diff --git a/apps/opencs/model/world/data.hpp b/apps/opencs/model/world/data.hpp
index f0c3dcd417..dc00a33d2e 100644
--- a/apps/opencs/model/world/data.hpp
+++ b/apps/opencs/model/world/data.hpp
@@ -123,6 +123,8 @@ namespace CSMWorld
 
             std::vector<boost::shared_ptr<ESM::ESMReader> > mReaders;
 
+            std::map<std::string, int> mContentFileNames;
+
             // not implemented
             Data (const Data&);
             Data& operator= (const Data&);