diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index 4d9f042fddedc..64fa93381449f 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -782,7 +782,7 @@ impl<T: fmt::Debug, E> Result<T, E> {
 #[inline(never)]
 #[cold]
 fn unwrap_failed<E: fmt::Debug>(msg: &str, error: E) -> ! {
-    panic!("{}: {:?}", msg, error)
+    panic!("{}: {:#?}", msg, error)
 }
 
 /////////////////////////////////////////////////////////////////////////////