diff --git a/AMDiS/src/DOFVector.h b/AMDiS/src/DOFVector.h
index c0ffe79c2c826add25849cedaf2d4bf44976698f..2d42e1286eaa00db0b0df5605fea9f5a6bb5333e 100644
--- a/AMDiS/src/DOFVector.h
+++ b/AMDiS/src/DOFVector.h
@@ -540,7 +540,7 @@ namespace AMDiS {
      */
     void interpol(AbstractFunction<T, WorldVector<double> > *fct);
 
-    void interpol(DOFVector<T> *v, double factor);
+    void interpol(DOFVector<T> *v, double factor=1.0);
 
     /// Writes the data of the DOFVector to an output stream.
     void serialize(std::ostream &out)