diff --git a/extensions/VtuReader.hh b/extensions/VtuReader.hh
index 5187b7b206d99fc3c48c17875c31e4a766e55ebd..b1e9b13dae11029800ac12477fe087d307a4bcdf 100644
--- a/extensions/VtuReader.hh
+++ b/extensions/VtuReader.hh
@@ -78,7 +78,7 @@ namespace AMDiS {
 	    int nComponents = -1;
 	    if (DataArray.attribute("NumberOfComponents"))
 	      nComponents = DataArray.attribute("NumberOfComponents").as_int();
-	    if (nComponents != -1 && vector_operations::num_rows(test) > nComponents)
+	    if (nComponents != -1 && static_cast<int>(vector_operations::num_rows(test)) > nComponents)
 	      throw(std::runtime_error("Can not store values in DOFVector with given value type. Too many components!"));
 	    string2valueList(values, valueList[i], vector_operations::num_rows(test), nComponents);
 	    break;