diff --git a/include/tug/Boundary.hpp b/include/tug/Boundary.hpp
index 3a2df00..4989ba7 100644
--- a/include/tug/Boundary.hpp
+++ b/include/tug/Boundary.hpp
@@ -24,7 +24,7 @@ class Boundary {
          * @param grid
          * @param type  
          */
-        Boundary(Grid grid, BC_TYPE type);
+        Boundary(Grid &grid, BC_TYPE type);
 
         /**
          * @brief Get the Boundary Condition Type object
diff --git a/include/tug/Grid.hpp b/include/tug/Grid.hpp
index 35ccb2e..6af953c 100644
--- a/include/tug/Grid.hpp
+++ b/include/tug/Grid.hpp
@@ -49,7 +49,7 @@ class Grid {
         */
         void setAlpha(Matrix2d alpha_x, Matrix2d alpha_y);
 
-        auto getDim();
+        int getDim();
 
         auto getRow();
 
diff --git a/include/tug/Simulation.hpp b/include/tug/Simulation.hpp
index 468777c..17c1853 100644
--- a/include/tug/Simulation.hpp
+++ b/include/tug/Simulation.hpp
@@ -1,5 +1,4 @@
 #include "Boundary.hpp"
-#include "Grid.hpp"
 
 enum APPROACH {
     FTCS,
@@ -71,7 +70,6 @@ class Simulation {
         int iterations;
         CSV_OUTPUT csv_output;
 
-        Grid grid;
         Boundary bc;
         APPROACH approach;
 
diff --git a/src/Boundary.cpp b/src/Boundary.cpp
index 865a60f..150b9f2 100644
--- a/src/Boundary.cpp
+++ b/src/Boundary.cpp
@@ -3,7 +3,7 @@
 
 using namespace std;
 
-Boundary::Boundary(Grid grid, BC_TYPE type) {
+Boundary::Boundary(Grid &grid, BC_TYPE type) : grid(grid) {
     this->type = type;
 
     if (type == BC_TYPE_CONSTANT) {
diff --git a/src/Grid.cpp b/src/Grid.cpp
index 9b60a8d..4e92f01 100644
--- a/src/Grid.cpp
+++ b/src/Grid.cpp
@@ -35,7 +35,7 @@ void Grid::setAlpha(Matrix2d alpha_x, Matrix2d alpha_y) {
     this->alpha_y = alpha_y;
 }
 
-auto Grid::getDim() {
+int Grid::getDim() {
     return dim;
 }