diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 39cf2ec4c21..5992656ed25 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -1833,7 +1833,7 @@ pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
     ///
     /// # #[allow(dead_code)]
     /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> {
-    ///     let mut dst = Vec::with_capacity(elts);
+    ///     let mut dst: Vec<T> = Vec::with_capacity(elts);
     ///     dst.set_len(elts);
     ///     dst.as_mut_ptr().copy_from(ptr, elts);
     ///     dst
@@ -1872,7 +1872,7 @@ pub unsafe fn copy_from(self, src: *const T, count: usize)
     ///
     /// # #[allow(dead_code)]
     /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> {
-    ///     let mut dst = Vec::with_capacity(elts);
+    ///     let mut dst: Vec<T> = Vec::with_capacity(elts);
     ///     dst.set_len(elts);
     ///     dst.as_mut_ptr().copy_from_nonoverlapping(ptr, elts);
     ///     dst