diff --git a/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/EquipmentBlackBoxModel.java b/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/EquipmentBlackBoxModel.java
index 0e38d9f62..b8cd05588 100644
--- a/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/EquipmentBlackBoxModel.java
+++ b/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/EquipmentBlackBoxModel.java
@@ -15,5 +15,5 @@
 public interface EquipmentBlackBoxModel extends BlackBoxModel {
     String getStaticId();
 
-    Identifiable<?> getEquipment();
+    Identifiable<? extends Identifiable<?>> getEquipment();
 }
diff --git a/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/hvdc/AbstractHvdc.java b/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/hvdc/AbstractHvdc.java
index db28b7cff..2f32e5ef2 100644
--- a/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/hvdc/AbstractHvdc.java
+++ b/dynawaltz/src/main/java/com/powsybl/dynawaltz/models/hvdc/AbstractHvdc.java
@@ -63,7 +63,7 @@ protected final VarConnection getSimpleVarConnectionWithBus(EquipmentConnectionP
         return new VarConnection(TERMINAL_PREFIX + side.getSideNumber(), connected.getTerminalVarName(side));
     }
 
-    public List<HvdcConverterStation<?>> getConnectedStations() {
+    public List<HvdcConverterStation<? extends HvdcConverterStation<?>>> getConnectedStations() {
         return List.of(equipment.getConverterStation1(), equipment.getConverterStation2());
     }
 }