diff --git a/src/libstd/io/extensions.rs b/src/libstd/io/extensions.rs
index 26e0a0d09ad..f6e87212d17 100644
--- a/src/libstd/io/extensions.rs
+++ b/src/libstd/io/extensions.rs
@@ -366,7 +366,7 @@ mod test {
     fn push_bytes_fail_reset_len() {
         // push_bytes unsafely sets the vector length. This is testing that
         // upon failure the length is reset correctly.
-        let reader = ErroringLaterReader {
+        let _reader = ErroringLaterReader {
             count: 0,
         };
         // FIXME (#7049): Figure out some other way to do this.
diff --git a/src/libstd/io/net/addrinfo.rs b/src/libstd/io/net/addrinfo.rs
index a1650c9a3a3..29bf6261a07 100644
--- a/src/libstd/io/net/addrinfo.rs
+++ b/src/libstd/io/net/addrinfo.rs
@@ -102,10 +102,6 @@ fn lookup(hostname: Option<&str>, servname: Option<&str>, hint: Option<Hint>)
 // permission without help of apk
 #[cfg(test, not(target_os = "android"))]
 mod test {
-    use io::net::ip::Ipv4Addr;
-    use prelude::*;
-    use super::*;
-
     iotest!(fn dns_smoke_test() {
         let ipaddrs = get_host_addresses("localhost").unwrap();
         let mut found_local = false;
diff --git a/src/libstd/io/net/tcp.rs b/src/libstd/io/net/tcp.rs
index fc608ce25a6..475e3b206f2 100644
--- a/src/libstd/io/net/tcp.rs
+++ b/src/libstd/io/net/tcp.rs
@@ -632,7 +632,7 @@ mod test {
 
         spawn(proc() {
             port.recv();
-            let stream = TcpStream::connect(addr);
+            let _stream = TcpStream::connect(addr);
             // Close
             port.recv();
         });
@@ -641,12 +641,12 @@ mod test {
             let mut acceptor = TcpListener::bind(addr).listen();
             chan.send(());
             {
-                let stream = acceptor.accept();
+                let _stream = acceptor.accept();
                 // Close client
                 chan.send(());
             }
             // Close listener
         }
-        let listener = TcpListener::bind(addr);
+        let _listener = TcpListener::bind(addr);
     })
 }
diff --git a/src/libstd/num/f32.rs b/src/libstd/num/f32.rs
index 0af8f155c68..8acfd197618 100644
--- a/src/libstd/num/f32.rs
+++ b/src/libstd/num/f32.rs
@@ -907,7 +907,6 @@ mod tests {
 
     use num::*;
     use num;
-    use mem;
 
     #[test]
     fn test_num() {
diff --git a/src/libstd/num/f64.rs b/src/libstd/num/f64.rs
index 1155a89876e..6bb7bf6c563 100644
--- a/src/libstd/num/f64.rs
+++ b/src/libstd/num/f64.rs
@@ -909,7 +909,6 @@ mod tests {
 
     use num::*;
     use num;
-    use mem;
 
     #[test]
     fn test_num() {
diff --git a/src/libstd/num/int_macros.rs b/src/libstd/num/int_macros.rs
index ca65ade4069..c0f67912cde 100644
--- a/src/libstd/num/int_macros.rs
+++ b/src/libstd/num/int_macros.rs
@@ -444,7 +444,6 @@ mod tests {
     use num;
     use num::CheckedDiv;
     use num::Bitwise;
-    use mem;
 
     #[test]
     fn test_num() {
diff --git a/src/libstd/num/mod.rs b/src/libstd/num/mod.rs
index 28f0cfbce15..956c04db09c 100644
--- a/src/libstd/num/mod.rs
+++ b/src/libstd/num/mod.rs
@@ -1075,7 +1075,6 @@ pub fn test_num<T:Num + NumCast>(ten: T, two: T) {
 mod tests {
     use prelude::*;
     use super::*;
-    use num;
     use i8;
     use i16;
     use i32;
diff --git a/src/libstd/num/uint_macros.rs b/src/libstd/num/uint_macros.rs
index 5b9767e68e8..224f16cc663 100644
--- a/src/libstd/num/uint_macros.rs
+++ b/src/libstd/num/uint_macros.rs
@@ -315,7 +315,6 @@ mod tests {
     use num;
     use num::CheckedDiv;
     use num::Bitwise;
-    use mem;
     use u16;
 
     #[test]
diff --git a/src/libstd/rt/unwind.rs b/src/libstd/rt/unwind.rs
index 16126ea1447..4d2dcb6c51c 100644
--- a/src/libstd/rt/unwind.rs
+++ b/src/libstd/rt/unwind.rs
@@ -77,7 +77,7 @@ mod libunwind {
     //! Unwind library interface
 
     #[allow(non_camel_case_types)];
-    #[allow(dead_code)] // these are just bindings
+    #[allow(dead_code)]; // these are just bindings
 
     use libc::{uintptr_t};