diff --git a/src/libcore/alloc.rs b/src/libcore/alloc.rs
index d260556a20803..65ff5d10e2de2 100644
--- a/src/libcore/alloc.rs
+++ b/src/libcore/alloc.rs
@@ -196,7 +196,7 @@ impl Layout {
         //    valid.
         //
         // 2. `len + align - 1` can overflow by at most `align - 1`,
-        //    so the &-mask wth `!(align - 1)` will ensure that in the
+        //    so the &-mask with `!(align - 1)` will ensure that in the
         //    case of overflow, `len_rounded_up` will itself be 0.
         //    Thus the returned padding, when added to `len`, yields 0,
         //    which trivially satisfies the alignment `align`.