diff --git a/python/core/qgsvectorfilewriter.sip b/python/core/qgsvectorfilewriter.sip
index 3db6aa9c680..5011070a649 100644
--- a/python/core/qgsvectorfilewriter.sip
+++ b/python/core/qgsvectorfilewriter.sip
@@ -21,7 +21,12 @@ public:
       NoError = 0,
       ErrDriverNotFound,
       ErrCreateDataSource,
-      ErrCreateLayer
+      ErrCreateLayer,
+      ErrAttributeTypeUnsupported,
+      ErrAttributeCreationFailed,
+      ErrProjection,  // added in 1.5
+      ErrFeatureWriteFailed, // added in 1.6
+      ErrInvalidLayer, // added in 2.0
     };
 
     /** Write contents of vector layer to a shapefile 
diff --git a/src/core/qgsvectorfilewriter.cpp b/src/core/qgsvectorfilewriter.cpp
index b5b6a5962e2..6de11eb7c93 100644
--- a/src/core/qgsvectorfilewriter.cpp
+++ b/src/core/qgsvectorfilewriter.cpp
@@ -588,6 +588,11 @@ QgsVectorFileWriter::writeAsVectorFormat( QgsVectorLayer* layer,
   QgsCoordinateTransform* ct = 0;
   int shallTransform = false;
 
+  if ( layer == NULL )
+  {
+    return ErrInvalidLayer;
+  }
+
   if ( destCRS && destCRS->isValid() )
   {
     // This means we should transform
diff --git a/src/core/qgsvectorfilewriter.h b/src/core/qgsvectorfilewriter.h
index 6322e71ce8e..851ce43cf56 100644
--- a/src/core/qgsvectorfilewriter.h
+++ b/src/core/qgsvectorfilewriter.h
@@ -53,6 +53,7 @@ class CORE_EXPORT QgsVectorFileWriter
       ErrAttributeCreationFailed,
       ErrProjection,  // added in 1.5
       ErrFeatureWriteFailed, // added in 1.6
+      ErrInvalidLayer, // added in 2.0
     };
 
     /** Write contents of vector layer to a shapefile