diff --git a/src/header/common/authorization.rs b/src/header/common/authorization.rs
index 98249bac..68c24c02 100644
--- a/src/header/common/authorization.rs
+++ b/src/header/common/authorization.rs
@@ -170,7 +170,7 @@ impl FromStr for Basic {
         match decode(s) {
             Ok(decoded) => match String::from_utf8(decoded) {
                 Ok(text) => {
-                    let mut parts = &mut text.split(':');
+                    let parts = &mut text.split(':');
                     let user = match parts.next() {
                         Some(part) => part.to_owned(),
                         None => return Err(::Error::Header)
diff --git a/src/header/common/link.rs b/src/header/common/link.rs
index 04783ba4..0395801f 100644
--- a/src/header/common/link.rs
+++ b/src/header/common/link.rs
@@ -495,7 +495,7 @@ impl FromStr for Link {
                     Some(p) => p.trim(),
                 };
 
-                let mut link_header = match link_values.last_mut() {
+                let link_header = match link_values.last_mut() {
                     None => return Err(::Error::Header),
                     Some(l) => l,
                 };
diff --git a/src/header/internals/cell.rs b/src/header/internals/cell.rs
index 21ded572..daf116a0 100644
--- a/src/header/internals/cell.rs
+++ b/src/header/internals/cell.rs
@@ -79,7 +79,7 @@ impl<V: ?Sized + Any + 'static> PtrMapCell<V> {
 
     #[inline]
     pub fn get_mut(&mut self, key: TypeId) -> Option<&mut V> {
-        let mut map = unsafe { &mut *self.0.get() };
+        let map = unsafe { &mut *self.0.get() };
         match *map {
             PtrMap::Empty => None,
             PtrMap::One(id, ref mut v) => if id == key {
@@ -107,7 +107,7 @@ impl<V: ?Sized + Any + 'static> PtrMapCell<V> {
 
     #[inline]
     pub unsafe fn insert(&self, key: TypeId, val: Box<V>) {
-        let mut map = &mut *self.0.get();
+        let map = &mut *self.0.get();
         match *map {
             PtrMap::Empty => *map = PtrMap::One(key, val),
             PtrMap::One(..) => {
diff --git a/src/http/conn.rs b/src/http/conn.rs
index b86feb8e..608f7211 100644
--- a/src/http/conn.rs
+++ b/src/http/conn.rs
@@ -240,7 +240,7 @@ where I: AsyncRead + AsyncWrite,
 
         let wants_keep_alive = head.should_keep_alive();
         self.state.keep_alive &= wants_keep_alive;
-        let mut buf = self.io.write_buf_mut();
+        let buf = self.io.write_buf_mut();
         // if a 100-continue has started but not finished sending, tack the
         // remainder on to the start of the buffer.
         if let Writing::Continue(ref pending) = self.state.writing {
diff --git a/src/http/h1/decode.rs b/src/http/h1/decode.rs
index 609e5076..11438239 100644
--- a/src/http/h1/decode.rs
+++ b/src/http/h1/decode.rs
@@ -326,7 +326,7 @@ mod tests {
 
         fn read(s: &str) -> u64 {
             let mut state = ChunkedState::Size;
-            let mut rdr = &mut s.as_bytes();
+            let rdr = &mut s.as_bytes();
             let mut size = 0;
             loop {
                 let result = state.step(rdr, &mut size, &mut None);
@@ -341,7 +341,7 @@ mod tests {
 
         fn read_err(s: &str, expected_err: io::ErrorKind) {
             let mut state = ChunkedState::Size;
-            let mut rdr = &mut s.as_bytes();
+            let rdr = &mut s.as_bytes();
             let mut size = 0;
             loop {
                 let result = state.step(rdr, &mut size, &mut None);
diff --git a/src/http/io.rs b/src/http/io.rs
index 88c054e6..971a3e84 100644
--- a/src/http/io.rs
+++ b/src/http/io.rs
@@ -275,7 +275,7 @@ impl WriteBuf {
         trace!("WriteBuf::buffer() len = {:?}", data.len());
         self.maybe_reset();
         self.maybe_reserve(data.len());
-        let mut vec = &mut self.0.bytes;
+        let vec = &mut self.0.bytes;
         let len = cmp::min(vec.capacity() - vec.len(), data.len());
         assert!(vec.capacity() - vec.len() >= len);
         unsafe {
@@ -297,7 +297,7 @@ impl WriteBuf {
 
     #[inline]
     fn maybe_reserve(&mut self, needed: usize) {
-        let mut vec = &mut self.0.bytes;
+        let vec = &mut self.0.bytes;
         let cap = vec.capacity();
         if cap == 0 {
             let init = cmp::min(MAX_BUFFER_SIZE, cmp::max(INIT_BUFFER_SIZE, needed));