diff --git a/ebos/eclgenericoutputblackoilmodule.hh b/ebos/eclgenericoutputblackoilmodule.hh
index b2e7529b1..8d1b42f97 100644
--- a/ebos/eclgenericoutputblackoilmodule.hh
+++ b/ebos/eclgenericoutputblackoilmodule.hh
@@ -44,7 +44,7 @@
 
 namespace Opm {
 
-namespace data { struct Solution; }
+namespace data { class Solution; }
 class EclipseState;
 
 template<class FluidSystem, class Scalar>
diff --git a/opm/simulators/wells/BlackoilWellModelGeneric.hpp b/opm/simulators/wells/BlackoilWellModelGeneric.hpp
index 6e1d18a23..295e80650 100644
--- a/opm/simulators/wells/BlackoilWellModelGeneric.hpp
+++ b/opm/simulators/wells/BlackoilWellModelGeneric.hpp
@@ -48,7 +48,7 @@ namespace Opm {
 namespace data {
 struct GroupData;
 struct GroupGuideRates;
-struct GroupAndNetworkValues;
+class GroupAndNetworkValues;
 struct NodeData;
 }