diff --git a/apps/opencs/model/world/data.hpp b/apps/opencs/model/world/data.hpp
index d59b836070..88a431fb74 100644
--- a/apps/opencs/model/world/data.hpp
+++ b/apps/opencs/model/world/data.hpp
@@ -104,7 +104,7 @@ namespace CSMWorld
             const ESM::Dialogue *mDialogue; // last loaded dialogue
             bool mBase;
             bool mProject;
-            std::map<std::string, std::map<ESM::RefNum, std::string> > mRefLoadCache;
+            std::map<std::string, std::map<unsigned int, std::string> > mRefLoadCache;
             int mReaderIndex;
 
             std::vector<boost::shared_ptr<ESM::ESMReader> > mReaders;
diff --git a/apps/opencs/model/world/refcollection.cpp b/apps/opencs/model/world/refcollection.cpp
index 117aeb0121..f811131a19 100644
--- a/apps/opencs/model/world/refcollection.cpp
+++ b/apps/opencs/model/world/refcollection.cpp
@@ -12,7 +12,7 @@
 #include "record.hpp"
 
 void CSMWorld::RefCollection::load (ESM::ESMReader& reader, int cellIndex, bool base,
-    std::map<ESM::RefNum, std::string>& cache, CSMDoc::Messages& messages)
+    std::map<unsigned int, std::string>& cache, CSMDoc::Messages& messages)
 {
     Record<Cell> cell = mCells.getRecord (cellIndex);
 
@@ -71,13 +71,7 @@ void CSMWorld::RefCollection::load (ESM::ESMReader& reader, int cellIndex, bool
         else
             ref.mCell = cell2.mId;
 
-        // ignore content file number
-        std::map<ESM::RefNum, std::string>::iterator iter = cache.begin();
-        for (; iter != cache.end(); ++iter)
-        {
-            if (ref.mRefNum.mIndex == iter->first.mIndex)
-                break;
-        }
+        std::map<unsigned int, std::string>::iterator iter = cache.find (ref.mRefNum.mIndex);
 
         if (isDeleted)
         {
@@ -114,11 +108,12 @@ void CSMWorld::RefCollection::load (ESM::ESMReader& reader, int cellIndex, bool
 
             std::unique_ptr<Record<CellRef> > record(new Record<CellRef>);
             record->mState = base ? RecordBase::State_BaseOnly : RecordBase::State_ModifiedOnly;
+
+            cache.insert (std::make_pair (ref.mRefNum.mIndex, ref.mId));
+
             (base ? record->mBase : record->mModified) = std::move(ref);
 
             appendRecord(std::move(record));
-
-            cache.insert (std::make_pair (ref.mRefNum, ref.mId));
         }
         else
         {
diff --git a/apps/opencs/model/world/refcollection.hpp b/apps/opencs/model/world/refcollection.hpp
index d031398d3f..42bb363570 100644
--- a/apps/opencs/model/world/refcollection.hpp
+++ b/apps/opencs/model/world/refcollection.hpp
@@ -27,7 +27,7 @@ namespace CSMWorld
             {}
 
             void load (ESM::ESMReader& reader, int cellIndex, bool base,
-                std::map<ESM::RefNum, std::string>& cache, CSMDoc::Messages& messages);
+                std::map<unsigned int, std::string>& cache, CSMDoc::Messages& messages);
             ///< Load a sequence of references.
 
             std::string getNewId();