diff --git a/opm/simulators/wells/BlackoilWellModelGuideRates.hpp b/opm/simulators/wells/BlackoilWellModelGuideRates.hpp
index d481b14e4..be97a86be 100644
--- a/opm/simulators/wells/BlackoilWellModelGuideRates.hpp
+++ b/opm/simulators/wells/BlackoilWellModelGuideRates.hpp
@@ -33,7 +33,7 @@ namespace Opm {
 class BlackoilWellModelGeneric;
 namespace data {
 struct GroupData;
-class GroupGuideRates;
+struct GroupGuideRates;
 class GuideRateValue;
 class Wells;
 }
diff --git a/opm/simulators/wells/BlackoilWellModelRestart.hpp b/opm/simulators/wells/BlackoilWellModelRestart.hpp
index 09e6e4c41..b90fdbeec 100644
--- a/opm/simulators/wells/BlackoilWellModelRestart.hpp
+++ b/opm/simulators/wells/BlackoilWellModelRestart.hpp
@@ -32,14 +32,14 @@ namespace Opm {
 
 class BlackoilWellModelGeneric;
 namespace data {
-class GroupData;
+struct GroupData;
 class GroupAndNetworkValues;
 }
 class GroupState;
 class GuideRate;
 class GuideRateConfig;
 struct PerforationData;
-class PhaseUsage;
+struct PhaseUsage;
 class SingleWellState;
 class WellState;
 
diff --git a/opm/simulators/wells/WellTest.hpp b/opm/simulators/wells/WellTest.hpp
index c643207d9..de0521390 100644
--- a/opm/simulators/wells/WellTest.hpp
+++ b/opm/simulators/wells/WellTest.hpp
@@ -31,7 +31,7 @@ namespace Opm
 {
 
 class DeferredLogger;
-class PhaseUsage;
+struct PhaseUsage;
 class SingleWellState;
 class WellEconProductionLimits;
 class WellInterfaceGeneric;