diff --git a/src/libcore/char.rs b/src/libcore/char.rs
index 1fe840650dc9..272b36847991 100644
--- a/src/libcore/char.rs
+++ b/src/libcore/char.rs
@@ -225,9 +225,9 @@ pub trait Char {
     /// Returns `true` if `c` is a valid digit under `radix`, and `false`
     /// otherwise.
     ///
-    /// # Failure
+    /// # Panics
     ///
-    /// Fails if given a radix > 36.
+    /// Panics if given a radix > 36.
     #[unstable = "pending error conventions"]
     fn is_digit(self, radix: uint) -> bool;