diff --git a/src/discouraged.rs b/src/discouraged.rs
index 6e3b43d..3626126 100644
--- a/src/discouraged.rs
+++ b/src/discouraged.rs
@@ -151,7 +151,9 @@
     ///
     /// # Panics
     ///
-    /// The forked stream that this joins with must be derived by forking this parse stream.
+    /// The forked stream in the argument of `advance_to` must have been
+    /// obtained by forking `self`. Attempting to advance to any other stream
+    /// will cause a panic.
     fn advance_to(&self, fork: &Self);
 }