diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 0117db25c58..68966d21984 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -146,7 +146,7 @@ fn to_unsafe_ptr<T>(thing: &T) -> *T unsafe {
 */
 #[inline(always)]
 fn to_mut_unsafe_ptr<T>(thing: &mut T) -> *mut T unsafe {
-    unsafe::reinterpret_cast(thing)
+    unsafe::reinterpret_cast(&thing)
 }
 
 /**