diff --git a/src/mapserver/qgshostedrdsbuilder.cpp b/src/mapserver/qgshostedrdsbuilder.cpp
index 96bff620a0fa..ff3072b3f142 100644
--- a/src/mapserver/qgshostedrdsbuilder.cpp
+++ b/src/mapserver/qgshostedrdsbuilder.cpp
@@ -67,7 +67,7 @@ QgsMapLayer* QgsHostedRDSBuilder::createMapLayer( const QDomElement& elem,
       rl = new QgsRasterLayer( uri, layerNameFromUri( uri ) );
       if ( allowCaching )
       {
-        QgsMSLayerCache::instance()->insertLayer( uri, layerName, rl, "" /*todo: add project file path*/ );
+        QgsMSLayerCache::instance()->insertLayer( uri, layerName, rl );
       }
       else
       {
diff --git a/src/mapserver/qgshostedvdsbuilder.cpp b/src/mapserver/qgshostedvdsbuilder.cpp
index a3837be19b6d..07ca7b6fc6da 100644
--- a/src/mapserver/qgshostedvdsbuilder.cpp
+++ b/src/mapserver/qgshostedvdsbuilder.cpp
@@ -75,7 +75,7 @@ QgsMapLayer* QgsHostedVDSBuilder::createMapLayer( const QDomElement& elem,
 
     if ( allowCaching )
     {
-      QgsMSLayerCache::instance()->insertLayer( uri, layerName, ml, "" /*todo: add project file path*/ );
+      QgsMSLayerCache::instance()->insertLayer( uri, layerName, ml );
     }
     else
     {
diff --git a/src/mapserver/qgsmslayercache.cpp b/src/mapserver/qgsmslayercache.cpp
index 038567c44cac..2ff2317b4aee 100644
--- a/src/mapserver/qgsmslayercache.cpp
+++ b/src/mapserver/qgsmslayercache.cpp
@@ -75,15 +75,18 @@ void QgsMSLayerCache::insertLayer( const QString& url, const QString& layerName,
   mEntries.insert( urlLayerPair, newEntry );
 
   //update config file map
-  QHash< QString, int >::iterator configIt = mConfigFiles.find( configFile );
-  if ( configIt == mConfigFiles.end() )
+  if ( !configFile.isEmpty() )
   {
-    mConfigFiles.insert( configFile, 1 );
-    mFileSystemWatcher.addPath( configFile );
-  }
-  else
-  {
-    mConfigFiles[configFile] = configIt.value() + 1; //increment reference counter
+    QHash< QString, int >::iterator configIt = mConfigFiles.find( configFile );
+    if ( configIt == mConfigFiles.end() )
+    {
+      mConfigFiles.insert( configFile, 1 );
+      mFileSystemWatcher.addPath( configFile );
+    }
+    else
+    {
+      mConfigFiles[configFile] = configIt.value() + 1; //increment reference counter
+    }
   }
 }
 
@@ -190,14 +193,17 @@ void QgsMSLayerCache::freeEntryRessources( QgsMSLayerCacheEntry& entry )
   }
 
   //counter
-  int configFileCount = mConfigFiles[entry.configFile];
-  if ( configFileCount < 2 )
+  if ( !entry.configFile.isEmpty() )
   {
-    mConfigFiles.remove( entry.configFile );
-    mFileSystemWatcher.removePath( entry.configFile );
-  }
-  else
-  {
-    mConfigFiles[entry.configFile] = configFileCount - 1;
+    int configFileCount = mConfigFiles[entry.configFile];
+    if ( configFileCount < 2 )
+    {
+      mConfigFiles.remove( entry.configFile );
+      mFileSystemWatcher.removePath( entry.configFile );
+    }
+    else
+    {
+      mConfigFiles[entry.configFile] = configFileCount - 1;
+    }
   }
 }
diff --git a/src/mapserver/qgsmslayercache.h b/src/mapserver/qgsmslayercache.h
index b45166647f86..d74a1b3dab6e 100644
--- a/src/mapserver/qgsmslayercache.h
+++ b/src/mapserver/qgsmslayercache.h
@@ -48,8 +48,9 @@ class QgsMSLayerCache: public QObject
     /**Inserts a new layer into the cash
     @param url the layer datasource
     @param layerName the layer name (to distinguish between different layers in a request using the same datasource
+    @param configFile path of the config file (to invalidate entries if file changes). Can be empty (e.g. layers from sld)
     @param tempFiles some layers have temporary files. The cash makes sure they are removed when removing the layer from the cash*/
-    void insertLayer( const QString& url, const QString& layerName, QgsMapLayer* layer, const QString& configFile, const QList<QString>& tempFiles = QList<QString>() );
+    void insertLayer( const QString& url, const QString& layerName, QgsMapLayer* layer, const QString& configFile = QString(), const QList<QString>& tempFiles = QList<QString>() );
     /**Searches for the layer with the given url.
      @return a pointer to the layer or 0 if no such layer*/
     QgsMapLayer* searchLayer( const QString& url, const QString& layerName );
diff --git a/src/mapserver/qgsremoteowsbuilder.cpp b/src/mapserver/qgsremoteowsbuilder.cpp
index ee7ebccb8a5e..bd93ff580bfd 100644
--- a/src/mapserver/qgsremoteowsbuilder.cpp
+++ b/src/mapserver/qgsremoteowsbuilder.cpp
@@ -115,7 +115,7 @@ QgsMapLayer* QgsRemoteOWSBuilder::createMapLayer(
     {
       if ( allowCaching )
       {
-        QgsMSLayerCache::instance()->insertLayer( url, layerName, result, "" /*todo: add project file path*/ );
+        QgsMSLayerCache::instance()->insertLayer( url, layerName, result );
       }
       else
       {
@@ -215,7 +215,7 @@ QgsRasterLayer* QgsRemoteOWSBuilder::wmsLayerFromUrl( const QString& url, const
   //insert into cache
   if ( allowCaching )
   {
-    QgsMSLayerCache::instance()->insertLayer( url, layerName, result, "" /*todo: add project file path*/ );
+    QgsMSLayerCache::instance()->insertLayer( url, layerName, result );
   }
   else
   {
@@ -414,7 +414,7 @@ QgsVectorLayer* QgsRemoteOWSBuilder::sosLayer( const QDomElement& remoteOWSElem,
   {
     if ( allowCaching )
     {
-      QgsMSLayerCache::instance()->insertLayer( providerUrl, layerName, sosLayer, "" /*todo: add project file path*/ );
+      QgsMSLayerCache::instance()->insertLayer( providerUrl, layerName, sosLayer );
     }
     else
     {