diff --git a/crates/border-wars/src/camera.rs b/crates/border-wars/src/camera.rs
index 8d5ac73..29c193b 100644
--- a/crates/border-wars/src/camera.rs
+++ b/crates/border-wars/src/camera.rs
@@ -104,6 +104,7 @@ fn keyboard_movement_system(
     }
 }
 
+/// Moves the camera with mouse input.
 fn mouse_movement_system(
     mouse_button_input: Res<Input<MouseButton>>,
     mut query: Query<&mut Transform, With<Camera>>,