diff --git a/src/activity_actor_definitions.h b/src/activity_actor_definitions.h
index 2e2e9d84ba057..eeac84fc28b8c 100644
--- a/src/activity_actor_definitions.h
+++ b/src/activity_actor_definitions.h
@@ -1485,7 +1485,7 @@ class vehicle_folding_activity_actor : public activity_actor
         bool fold_vehicle( Character &p, bool check_only ) const;
 
         // private empty constructor for deserialization
-        vehicle_folding_activity_actor() {}
+        explicit vehicle_folding_activity_actor() = default;
     public:
         vehicle_folding_activity_actor( const vehicle &target );
 
@@ -1518,7 +1518,7 @@ class vehicle_unfolding_activity_actor : public activity_actor
         bool unfold_vehicle( Character &p, bool check_only ) const;
 
         // private empty constructor for deserialization
-        vehicle_unfolding_activity_actor() {}
+        explicit vehicle_unfolding_activity_actor() = default;
     public:
         vehicle_unfolding_activity_actor( const item &it );