diff --git a/nav2_costmap_2d/plugins/costmap_filters/costmap_filter.cpp b/nav2_costmap_2d/plugins/costmap_filters/costmap_filter.cpp
index bc4e89f878e..06d7ed2d025 100644
--- a/nav2_costmap_2d/plugins/costmap_filters/costmap_filter.cpp
+++ b/nav2_costmap_2d/plugins/costmap_filters/costmap_filter.cpp
@@ -222,7 +222,7 @@ unsigned char CostmapFilter::getMaskCost(
 {
   const unsigned int index = my * filter_mask->info.width + mx;
 
-  const char data = filter_mask->data[index];
+  const signed char data = filter_mask->data[index];
   if (data == nav2_util::OCC_GRID_UNKNOWN) {
     return NO_INFORMATION;
   } else {