diff --git a/include/Residual/residual.h b/include/Residual/residual.h
index c39824d2..19dcc46a 100644
--- a/include/Residual/residual.h
+++ b/include/Residual/residual.h
@@ -30,8 +30,8 @@ class Residual
 protected:
     /* ------------------- */
     /* Constructor members */
-    const PolarGrid grid_;
-    const LevelCacheType level_cache_;
+    const PolarGrid& grid_;
+    const LevelCacheType& level_cache_;
     const bool DirBC_Interior_;
 };
 } // namespace gmgpolar
diff --git a/include/Smoother/smoother.h b/include/Smoother/smoother.h
index 3c659563..a2ca435d 100644
--- a/include/Smoother/smoother.h
+++ b/include/Smoother/smoother.h
@@ -33,14 +33,13 @@ class Smoother
         , DirBC_Interior_(DirBC_Interior)
     {
     }
-    KOKKOS_DEFAULTED_FUNCTION Smoother(const Smoother&) = default;
-    virtual ~Smoother()                                 = default;
+    virtual ~Smoother() = default;
 
     virtual void smoothing(Vector<double> x, ConstVector<double> rhs, Vector<double> temp) = 0;
 
 protected:
-    const PolarGrid grid_;
-    const LevelCacheType level_cache_;
+    const PolarGrid& grid_;
+    const LevelCacheType& level_cache_;
     const bool DirBC_Interior_;
 };
 } // namespace gmgpolar