diff --git a/fortran/tuvx.F90 b/fortran/tuvx.F90
index 210e9c2c..55d8e1cb 100644
--- a/fortran/tuvx.F90
+++ b/fortran/tuvx.F90
@@ -50,19 +50,19 @@ end function get_grid_c
       subroutine set_edges_c(grid, edges, n_edges, error) bind(C, name="SetEdges")
          use musica_util, only: error_t_c
          import c_ptr, c_double, c_size_t
-         type(c_ptr), value, intent(in) :: grid
+         type(c_ptr), value, intent(in)           :: grid
          real(c_double), dimension(*), intent(in) :: edges
-         integer(c_size_t), intent(in) :: n_edges
-         type(error_t_c), intent(inout) :: error
+         integer(c_size_t), value                 :: n_edges
+         type(error_t_c), intent(inout)           :: error
       end subroutine set_edges_c
 
       subroutine set_midpoints_c(grid, midpoints, n_midpoints, error) bind(C, name="SetMidpoints")
          use musica_util, only: error_t_c
          import c_ptr, c_double, c_size_t
-         type(c_ptr), value, intent(in) :: grid
+         type(c_ptr), value, intent(in)           :: grid
          real(c_double), dimension(*), intent(in) :: midpoints
-         integer(c_size_t), intent(in) :: n_midpoints
-         type(error_t_c), intent(inout) :: error
+         integer(c_size_t), value                 :: n_midpoints
+         type(error_t_c), intent(inout)           :: error
       end subroutine set_midpoints_c
 
    end interface
diff --git a/src/test/unit/tuvx/tuvx_c_api.cpp b/src/test/unit/tuvx/tuvx_c_api.cpp
index b6191725..8eb1f969 100644
--- a/src/test/unit/tuvx/tuvx_c_api.cpp
+++ b/src/test/unit/tuvx/tuvx_c_api.cpp
@@ -56,9 +56,22 @@ TEST_F(TuvxCApiTest, DetectsNonexistentConfigFile) {
     DeleteError(&error);
 }
 
-TEST_F(TuvxCApiTest, GridMap) {
+TEST_F(TuvxCApiTest, CanGetGrid) {
+    const char* yaml_config_path = "examples/ts1_tsmlt.yml";
+    SetUp(yaml_config_path);
+    Error error;
+    GridMap* grid_map = GetGridMap(tuvx, &error);
+    ASSERT_TRUE(IsSuccess(error));
+    ASSERT_NE(grid_map, nullptr);
+    Grid* grid = GetGrid(grid_map, "height", "km", &error);
+    ASSERT_TRUE(IsSuccess(error));
+    ASSERT_NE(grid, nullptr);
+    std::vector<double> edges = {0.0, 1.0, 2.0};
+    ASSERT_NO_THROW(
+        SetEdges(grid, edges.data(), edges.size(), &error);
+    );
+    std::vector<double> midpoints = {0.5, 1.5};
+    ASSERT_NO_THROW(
+        SetMidpoints(grid, midpoints.data(), midpoints.size(), &error);
+    );
 }
-
-TEST_F(TuvxCApiTest, Grid) {
-
-}
\ No newline at end of file
diff --git a/src/tuvx/interface.F90 b/src/tuvx/interface.F90
index f1ba9c97..2ba11bc4 100644
--- a/src/tuvx/interface.F90
+++ b/src/tuvx/interface.F90
@@ -157,12 +157,12 @@ end subroutine internal_delete_grid
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
     subroutine internal_set_edges(grid, edges, num_edges, error_code) bind(C, name="InternalSetEdges")
-      use iso_c_binding, only: c_ptr, c_f_pointer, c_int, c_double
+      use iso_c_binding, only: c_ptr, c_f_pointer, c_int, c_double, c_size_t
     
       ! arguments
       type(c_ptr), value, intent(in)                :: grid
       real(kind=c_double), intent(in), dimension(*) :: edges
-      integer(kind=c_int), intent(in)               :: num_edges
+      integer(kind=c_size_t), intent(in), value     :: num_edges
       integer(kind=c_int), intent(out)              :: error_code
     
       ! variables
@@ -174,6 +174,8 @@ subroutine internal_set_edges(grid, edges, num_edges, error_code) bind(C, name="
 
       f_grid%delta_ = edges(2:num_edges) - edges(1:num_edges-1)
 
+      f_grid%ncells_ = num_edges - 1
+
     end subroutine internal_set_edges
 
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@@ -184,7 +186,7 @@ subroutine internal_set_midpoints(grid, midpoints, num_midpoints, error_code) bi
       ! arguments
       type(c_ptr), value, intent(in)                :: grid
       real(kind=c_double), intent(in), dimension(*) :: midpoints
-      integer(kind=c_int), intent(in)               :: num_midpoints
+      integer(kind=c_int), intent(in), value        :: num_midpoints
       integer(kind=c_int), intent(out)              :: error_code
     
       ! variables