diff --git a/Design-Doc%3A-%60level%60-tool.md b/Design-Doc%3A-%60level%60-tool.md
index 833c380..a4a16f2 100644
--- a/Design-Doc%3A-%60level%60-tool.md
+++ b/Design-Doc%3A-%60level%60-tool.md
@@ -70,7 +70,7 @@ While the above format contains the graphics, this contains the nametable settin
 ### .lvc Format (Level Collision Map)
 The collision map is just an array of 8-bit unsigned integers laid out with the same tile dimensions as your visible layers. 0 is a free area, while 1 is a collision area.
 
-### .ent Format (Entity-Component System)
+### .ecs Format (Entity-Component System)
 This file contains the entity-component system defined by the [attributes](#entity-component-system) set in Tiled Map Editor's object layer(s).
 
 #### Entity Data