diff --git a/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother.hpp b/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother.hpp
index a0d5dfa115e..f37b40ac3bc 100644
--- a/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother.hpp
+++ b/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother.hpp
@@ -142,10 +142,10 @@ class Smoother
     std::vector<bool> & optimized)
   {
     // Create costmap grid
-    costmap_grid_ = std::make_shared<ceres::Grid2D<u_char>>(
+    costmap_grid_ = std::make_shared<ceres::Grid2D<unsigned char>>(
       costmap->getCharMap(), 0, costmap->getSizeInCellsY(), 0, costmap->getSizeInCellsX());
-    auto costmap_interpolator = std::make_shared<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>>(
-      *costmap_grid_);
+    auto costmap_interpolator =
+      std::make_shared<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>>(*costmap_grid_);
 
     // Create residual blocks
     const double cusp_half_length = params.cusp_zone_length / 2;
@@ -394,7 +394,7 @@ class Smoother
 
   bool debug_;
   ceres::Solver::Options options_;
-  std::shared_ptr<ceres::Grid2D<u_char>> costmap_grid_;
+  std::shared_ptr<ceres::Grid2D<unsigned char>> costmap_grid_;
 };
 
 }  // namespace nav2_constrained_smoother
diff --git a/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother_cost_function.hpp b/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother_cost_function.hpp
index 7253119721c..adfae2bc242 100644
--- a/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother_cost_function.hpp
+++ b/nav2_constrained_smoother/include/nav2_constrained_smoother/smoother_cost_function.hpp
@@ -57,7 +57,8 @@ class SmootherCostFunction
     double next_to_last_length_ratio,
     bool reversing,
     const nav2_costmap_2d::Costmap2D * costmap,
-    const std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>> & costmap_interpolator,
+    const std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>> &
+    costmap_interpolator,
     const SmootherParams & params,
     double costmap_weight)
   : original_pos_(original_pos),
@@ -244,7 +245,7 @@ class SmootherCostFunction
   double costmap_weight_;
   Eigen::Vector2d costmap_origin_;
   double costmap_resolution_;
-  std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>> costmap_interpolator_;
+  std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>> costmap_interpolator_;
 };
 
 }  // namespace nav2_constrained_smoother
diff --git a/nav2_constrained_smoother/test/test_smoother_cost_function.cpp b/nav2_constrained_smoother/test/test_smoother_cost_function.cpp
index 104b949c4be..24904ef5c55 100644
--- a/nav2_constrained_smoother/test/test_smoother_cost_function.cpp
+++ b/nav2_constrained_smoother/test/test_smoother_cost_function.cpp
@@ -33,7 +33,8 @@ class TestableSmootherCostFunction : nav2_constrained_smoother::SmootherCostFunc
     double next_to_last_length_ratio,
     bool reversing,
     const nav2_costmap_2d::Costmap2D * costmap,
-    const std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>> & costmap_interpolator,
+    const std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>> &
+    costmap_interpolator,
     const nav2_constrained_smoother::SmootherParams & params,
     double costmap_weight)
   : SmootherCostFunction(
@@ -68,7 +69,7 @@ TEST_F(Test, testingCurvatureResidual)
   nav2_costmap_2d::Costmap2D costmap;
   TestableSmootherCostFunction fn(
     Eigen::Vector2d(1.0, 0.0), 1.0, false,
-    &costmap, std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>>(),
+    &costmap, std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>>(),
     nav2_constrained_smoother::SmootherParams(), 0.0
   );
 
@@ -81,7 +82,7 @@ TEST_F(Test, testingCurvatureResidual)
   params_no_min_turning_radius.max_curvature = 1.0f / 0.0;
   TestableSmootherCostFunction fn_no_min_turning_radius(
     Eigen::Vector2d(1.0, 0.0), 1.0, false,
-    &costmap, std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<u_char>>>(),
+    &costmap, std::shared_ptr<ceres::BiCubicInterpolator<ceres::Grid2D<unsigned char>>>(),
     params_no_min_turning_radius, 0.0
   );
   EXPECT_EQ(fn_no_min_turning_radius.getCurvatureResidual(1.0, pt, pt_other, pt_other), 0.0);