diff --git a/src/state.rs b/src/state.rs
index 239139c..d151afc 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -1976,6 +1976,8 @@ impl Lua {
     }
 
     /// Returns an internal `Poll::Pending` constant used for executing async callbacks.
+    ///
+    /// Every time when [`Future`] is Pending, Lua corotine is suspended with this constant.
     #[cfg(feature = "async")]
     #[doc(hidden)]
     #[inline(always)]