diff --git a/common/systems/src/projectile.rs b/common/systems/src/projectile.rs
index daa4ac59fe..f5c4b3d4c8 100644
--- a/common/systems/src/projectile.rs
+++ b/common/systems/src/projectile.rs
@@ -160,6 +160,10 @@ impl<'a> System<'a> for Sys {
                             // We offset position a little back on the way,
                             // so if we hit non-exploadable block
                             // we still can affect blocks around it.
+                            //
+                            // TODO: orientation of fallen projectile is
+                            // fragile heuristic for direction, find more
+                            // robust method.
                             let projectile_direction = orientations
                                 .get(entity)
                                 .map_or_else(Vec3::zero, |ori| ori.look_vec());