diff --git a/src/BTCSDiffusion.cpp b/src/BTCSDiffusion.cpp
index 92855dc..da10b26 100644
--- a/src/BTCSDiffusion.cpp
+++ b/src/BTCSDiffusion.cpp
@@ -20,7 +20,7 @@ BTCSDiffusion::BTCSDiffusion(unsigned int dim) : grid_dim(dim) {
   deltas.resize(dim, 1);
 }
 
-void BTCSDiffusion::setXDimensions(unsigned int domain_size,
+void BTCSDiffusion::setXDimensions(double domain_size,
                                    unsigned int n_grid_cells) {
   assert(this->grid_dim > 0);
   this->domain_size[0] = domain_size;
@@ -29,7 +29,7 @@ void BTCSDiffusion::setXDimensions(unsigned int domain_size,
   updateInternals();
 }
 
-void BTCSDiffusion::setYDimensions(unsigned int domain_size,
+void BTCSDiffusion::setYDimensions(double domain_size,
                                    unsigned int n_grid_cells) {
   assert(this->grid_dim > 1);
   this->domain_size[1] = domain_size;
@@ -38,7 +38,7 @@ void BTCSDiffusion::setYDimensions(unsigned int domain_size,
   updateInternals();
 }
 
-void BTCSDiffusion::setZDimensions(unsigned int domain_size,
+void BTCSDiffusion::setZDimensions(double domain_size,
                                    unsigned int n_grid_cells) {
   assert(this->grid_dim > 2);
   this->domain_size[2] = domain_size;
diff --git a/src/BTCSDiffusion.hpp b/src/BTCSDiffusion.hpp
index ea3473d..7614ce5 100644
--- a/src/BTCSDiffusion.hpp
+++ b/src/BTCSDiffusion.hpp
@@ -48,7 +48,7 @@ public:
    * @param n_grid_cells Number of grid cells in x direction the domain is
    * divided to.
    */
-  void setXDimensions(unsigned int domain_size, unsigned int n_grid_cells);
+  void setXDimensions(double domain_size, unsigned int n_grid_cells);
 
   /*!
    * Define the grid in y direction.
@@ -59,7 +59,7 @@ public:
    * @param n_grid_cells Number of grid cells in y direction the domain is
    * divided to.
    */
-  void setYDimensions(unsigned int domain_size, unsigned int n_grid_cells);
+  void setYDimensions(double domain_size, unsigned int n_grid_cells);
 
   /*!
    * Define the grid in z direction.
@@ -70,7 +70,7 @@ public:
    * @param n_grid_cells Number of grid cells in z direction the domain is
    * divided to.
    */
-  void setZDimensions(unsigned int domain_size, unsigned int n_grid_cells);
+  void setZDimensions(double domain_size, unsigned int n_grid_cells);
 
   /*!
    * Returns the number of grid cells in x direction.