diff --git a/engine/tiles.go b/engine/tiles.go
index e38ea47..456a703 100644
--- a/engine/tiles.go
+++ b/engine/tiles.go
@@ -39,7 +39,7 @@ type Tilemap struct {
 	Disabled
 	Hidden
 	Map    map[image.Point]Tile // tilespace coordinate -> tile
-	Ersatz bool                 // "fake wall"
+	Ersatz bool                 // disables collisions ("fake wall")
 	Offset image.Point          // world coordinates
 	Sheet  Sheet
 	ZOrder
diff --git a/engine/walls.go b/engine/walls.go
index bbb1d76..d7f8336 100644
--- a/engine/walls.go
+++ b/engine/walls.go
@@ -29,7 +29,7 @@ var (
 // But Wall is still responsible for collisions.
 type Wall struct {
 	ID
-	Ersatz     bool        // fake wall - disables collisions
+	Ersatz     bool        // disables collisions ("fake wall")
 	Offset     image.Point //  offset the whole wall
 	Sheet      Sheet
 	UnitOffset image.Point // drawing offset