diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index 0f33d21ef02c..9ba1264f51e7 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -59,7 +59,6 @@ use core::char::CharExt;
 use core::clone::Clone;
 use core::iter::AdditiveIterator;
 use core::iter::{range, Iterator, IteratorExt};
-use core::kinds::Sized;
 use core::ops;
 use core::option::Option::{self, Some, None};
 use core::slice::AsSlice;
diff --git a/src/libcore/raw.rs b/src/libcore/raw.rs
index 0e91d6123f5c..5ef6f6b2623a 100644
--- a/src/libcore/raw.rs
+++ b/src/libcore/raw.rs
@@ -20,7 +20,6 @@
 
 use kinds::Copy;
 use mem;
-use kinds::Sized;
 
 /// The representation of a Rust slice
 #[repr(C)]
diff --git a/src/libcore/slice.rs b/src/libcore/slice.rs
index 9aa3f76b525e..1fde906062ec 100644
--- a/src/libcore/slice.rs
+++ b/src/libcore/slice.rs
@@ -1372,7 +1372,6 @@ pub unsafe fn from_raw_mut_buf<'a, T>(p: &'a *mut T, len: uint) -> &'a mut [T] {
 /// Operations on `[u8]`.
 #[experimental = "needs review"]
 pub mod bytes {
-    use kinds::Sized;
     use ptr;
     use slice::SliceExt;
 
diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index c0b9bbbbc297..abd4c7faa5bd 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -14,7 +14,6 @@
 
 #![unstable = "unsure about placement and naming"]
 
-use core::kinds::Sized;
 use iter::IteratorExt;
 use ops::FnMut;
 use slice::SliceExt;