diff --git a/src/events.rs b/src/events.rs
index ef5c6e9b..f3c21238 100644
--- a/src/events.rs
+++ b/src/events.rs
@@ -110,6 +110,9 @@ pub enum WindowEvent {
 pub enum DeviceEvent {
     Added,
     Removed,
+    /// Mouse devices yield `Motion` events where axis `0` is horizontal and axis `1` is vertical.
+    /// A positive value means a movement to the right or the bottom, depending on the axis.
+    /// Such events will be sent even if the mouse is in a corner of the screen.
     Motion { axis: AxisId, value: f64 },
     Button { button: ButtonId, state: ElementState },
     Key(KeyboardInput),