diff --git a/src/libcore/rt/uvio.rs b/src/libcore/rt/uvio.rs
index 7bf1792baf49b..abdd8d6619a8a 100644
--- a/src/libcore/rt/uvio.rs
+++ b/src/libcore/rt/uvio.rs
@@ -11,7 +11,7 @@
 use option::*;
 use result::*;
 
-use super::io::net::ip::{IpAddr, Ipv4}; // n.b. Ipv4 is used only in tests
+use super::io::net::ip::IpAddr;
 use super::uv::*;
 use super::rtio::*;
 use ops::Drop;
@@ -19,6 +19,7 @@ use cell::{Cell, empty_cell};
 use cast::transmute;
 use super::sched::{Scheduler, local_sched};
 
+#[cfg(test)] use super::io::net::ip::Ipv4;
 #[cfg(test)] use super::sched::Task;
 #[cfg(test)] use unstable::run_in_bare_thread;
 #[cfg(test)] use uint;
diff --git a/src/libcore/str/ascii.rs b/src/libcore/str/ascii.rs
index 339274ab47e4f..f6c0176eafc63 100644
--- a/src/libcore/str/ascii.rs
+++ b/src/libcore/str/ascii.rs
@@ -196,6 +196,7 @@ impl ToStrConsume for ~[Ascii] {
     }
 }
 
+#[cfg(test)]
 mod tests {
     use super::*;
 
diff --git a/src/librustc/back/link.rs b/src/librustc/back/link.rs
index 99ea0bc0c865e..8befa4c82031a 100644
--- a/src/librustc/back/link.rs
+++ b/src/librustc/back/link.rs
@@ -26,7 +26,7 @@ use core::char;
 use core::hash::Streaming;
 use core::hash;
 use core::io::WriterUtil;
-use core::libc::{c_int, c_uint, c_char};
+use core::libc::{c_int, c_uint};
 use core::os::consts::{macos, freebsd, linux, android, win32};
 use core::os;
 use core::ptr;
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index 68405f4fc5fe2..da87568b3d0c0 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -70,7 +70,7 @@ use core::hash;
 use core::hashmap::{HashMap, HashSet};
 use core::int;
 use core::io;
-use core::libc::{c_uint, c_ulonglong};
+use core::libc::c_uint;
 use core::uint;
 use std::time;
 use syntax::ast::ident;
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index b487fedf01dbb..47c9c3bdb6be4 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -514,7 +514,7 @@ pub struct substs {
 }
 
 mod primitives {
-    use super::{sty, t_box_};
+    use super::t_box_;
 
     use syntax::ast;