diff --git a/src/core/qgsgeometry.cpp b/src/core/qgsgeometry.cpp
index 304edf5db73..bcbdde3221a 100644
--- a/src/core/qgsgeometry.cpp
+++ b/src/core/qgsgeometry.cpp
@@ -5221,6 +5221,12 @@ bool QgsGeometry::exportGeosToWkb() const
 
 bool QgsGeometry::convertToMultiType()
 {
+  // TODO: implement with GEOS
+  if ( mDirtyWkb )
+  {
+    exportGeosToWkb();
+  }
+
   if ( !mGeometry )
   {
     return false;