diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 541de2d37fb..b92dfa9117e 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -75,7 +75,7 @@
 #![feature(box_syntax)]
 #![feature(optin_builtin_traits)]
 #![feature(unboxed_closures)]
-#![feature(unsafe_no_drop_flag)]
+#![feature(unsafe_no_drop_flag, filling_drop)]
 #![feature(core)]
 #![feature(unique)]
 #![cfg_attr(test, feature(test, alloc, rustc_private))]
diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs
index 6a65c991c95..e32ee34887c 100644
--- a/src/libcollections/lib.rs
+++ b/src/libcollections/lib.rs
@@ -36,7 +36,7 @@
 #![feature(unicode)]
 #![feature(unsafe_destructor)]
 #![feature(unique)]
-#![feature(unsafe_no_drop_flag)]
+#![feature(unsafe_no_drop_flag, filling_drop)]
 #![feature(step_by)]
 #![feature(str_char)]
 #![feature(convert)]
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 4b9e070619f..434a5d17a92 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -337,19 +337,28 @@ macro_rules! repeat_u8_as_u64 {
 // But having the sign bit set is a pain, so 0x1d is probably better.
 //
 // And of course, 0x00 brings back the old world of zero'ing on drop.
-#[cfg(not(stage0))] pub const POST_DROP_U8: u8 = 0x1d;
-#[cfg(not(stage0))] pub const POST_DROP_U32: u32 = repeat_u8_as_u32!(POST_DROP_U8);
-#[cfg(not(stage0))] pub const POST_DROP_U64: u64 = repeat_u8_as_u64!(POST_DROP_U8);
+#[cfg(not(stage0))] #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U8: u8 = 0x1d;
+#[cfg(not(stage0))] #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U32: u32 = repeat_u8_as_u32!(POST_DROP_U8);
+#[cfg(not(stage0))]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U64: u64 = repeat_u8_as_u64!(POST_DROP_U8);
 
 #[cfg(target_pointer_width = "32")]
-#[cfg(not(stage0))] pub const POST_DROP_USIZE: usize = POST_DROP_U32 as usize;
+#[cfg(not(stage0))]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_USIZE: usize = POST_DROP_U32 as usize;
 #[cfg(target_pointer_width = "64")]
-#[cfg(not(stage0))] pub const POST_DROP_USIZE: usize = POST_DROP_U64 as usize;
+#[cfg(not(stage0))]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_USIZE: usize = POST_DROP_U64 as usize;
 
-#[cfg(stage0)] pub const POST_DROP_U8: u8 = 0;
-#[cfg(stage0)] pub const POST_DROP_U32: u32 = 0;
-#[cfg(stage0)] pub const POST_DROP_U64: u64 = 0;
-#[cfg(stage0)] pub const POST_DROP_USIZE: usize = 0;
+#[cfg(stage0)]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U8: u8 = 0;
+#[cfg(stage0)]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U32: u32 = 0;
+#[cfg(stage0)]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_U64: u64 = 0;
+#[cfg(stage0)]  #[unstable(feature = "filling_drop")]
+pub const POST_DROP_USIZE: usize = 0;
 
 /// Interprets `src` as `&U`, and then reads `src` without moving the contained value.
 ///
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 7a9c9274f3b..07d018dea92 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -231,7 +231,7 @@ pub unsafe fn read_and_zero<T>(dest: *mut T) -> T {
 }
 
 /// Variant of read_and_zero that writes the specific drop-flag byte
-/// (which may be more apropriate than zero).
+/// (which may be more appropriate than zero).
 #[inline(always)]
 #[unstable(feature = "core",
            reason = "may play a larger role in std::ptr future extensions")]
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index cca6bb747d4..3724b26b202 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -121,7 +121,7 @@
 #![feature(unboxed_closures)]
 #![feature(unicode)]
 #![feature(unsafe_destructor)]
-#![feature(unsafe_no_drop_flag)]
+#![feature(unsafe_no_drop_flag, filling_drop)]
 #![feature(macro_reexport)]
 #![feature(int_uint)]
 #![feature(unique)]