1 files changed, 1 insertions, 1 deletions
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index 8a007d095d5..173233d7150 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -2754,7 +2754,7 @@ trait SizeHint {
     }
 }
 
-impl<T> SizeHint for T {
+impl<T: ?Sized> SizeHint for T {
     #[inline]
     default fn lower_bound(&self) -> usize {
         0