diff --git a/src/gamelib/grid_raytrace.cpp b/src/gamelib/grid_raytrace.cpp
index 8273fde..28aa2a0 100644
--- a/src/gamelib/grid_raytrace.cpp
+++ b/src/gamelib/grid_raytrace.cpp
@@ -138,10 +138,12 @@ namespace curry {
 		const vec2us last_tile = pixel_to_world_tile(parWorld, parTo);
 		while (parFunc(curr_tile) and last_tile != curr_tile) {
 			if (max.x() < max.y()) {
+				assert(std::max(static_cast<uint16_t>(curr_tile.x() + step.x()), last_tile.x()) - std::min(static_cast<uint16_t>(curr_tile.x() + step.x()), last_tile.x()) < std::max(curr_tile.x(), last_tile.x()) - std::min(curr_tile.x(), last_tile.x()));
 				max.x() += delta.x();
 				curr_tile.x() = static_cast<uint16_t>(curr_tile.x() + step.x());
 			}
 			else {
+				assert(std::max(static_cast<uint16_t>(curr_tile.y() + step.y()), last_tile.y()) - std::min(static_cast<uint16_t>(curr_tile.y() + step.y()), last_tile.y()) < std::max(curr_tile.y(), last_tile.y()) - std::min(curr_tile.y(), last_tile.y()));
 				max.y() += delta.y();
 				curr_tile.y() = static_cast<uint16_t>(curr_tile.y() + step.y());
 			}