diff --git a/src/common/accept_ranges.rs b/src/common/accept_ranges.rs
index e763fa9d..84da0369 100644
--- a/src/common/accept_ranges.rs
+++ b/src/common/accept_ranges.rs
@@ -1,5 +1,3 @@
-use http::HeaderValue;
-
 use util::FlatCsv;
 
 /// `Accept-Ranges` header, defined in [RFC7233](http://tools.ietf.org/html/rfc7233#section-2.3)
@@ -36,12 +34,12 @@ derive_header! {
     name: ACCEPT_RANGES
 }
 
-const ACCEPT_RANGES_BYTES: HeaderValue = ::HeaderValue::from_static("bytes");
+const ACCEPT_RANGES_BYTES: &str = "bytes";
 
 impl AcceptRanges {
     /// A constructor to easily create the common `Accept-Ranges: bytes` header.
     pub fn bytes() -> Self {
-        AcceptRanges(ACCEPT_RANGES_BYTES.into())
+        AcceptRanges(::HeaderValue::from_static(ACCEPT_RANGES_BYTES).into())
     }
 
     /// Check if the unit is `bytes`.
diff --git a/src/common/access_control_allow_headers.rs b/src/common/access_control_allow_headers.rs
index ca3d100d..ad5cff06 100644
--- a/src/common/access_control_allow_headers.rs
+++ b/src/common/access_control_allow_headers.rs
@@ -41,12 +41,12 @@ derive_header! {
 
 impl AccessControlAllowHeaders {
     /// Returns an iterator over `HeaderName`s contained within.
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = HeaderName> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = HeaderName> + '_ {
         self.0
             .iter()
             .map(|s| s.parse().ok())
             .take_while(|val| val.is_some())
-            .filter_map(|val| val)
+            .flatten()
     }
 }
 
diff --git a/src/common/access_control_allow_methods.rs b/src/common/access_control_allow_methods.rs
index 0fd1438c..e20ee7c1 100644
--- a/src/common/access_control_allow_methods.rs
+++ b/src/common/access_control_allow_methods.rs
@@ -42,7 +42,7 @@ derive_header! {
 
 impl AccessControlAllowMethods {
     /// Returns an iterator over `Method`s contained within.
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = Method> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = Method> + '_ {
         self.0.iter().filter_map(|s| s.parse().ok())
     }
 }
diff --git a/src/common/access_control_allow_origin.rs b/src/common/access_control_allow_origin.rs
index 8d38bf17..4d8778a9 100644
--- a/src/common/access_control_allow_origin.rs
+++ b/src/common/access_control_allow_origin.rs
@@ -105,7 +105,7 @@ impl TryFromValues for OriginOrAny {
 impl<'a> From<&'a OriginOrAny> for HeaderValue {
     fn from(origin: &'a OriginOrAny) -> HeaderValue {
         match origin {
-            OriginOrAny::Origin(ref origin) => origin.into_value(),
+            OriginOrAny::Origin(ref origin) => origin.to_value(),
             OriginOrAny::Any => HeaderValue::from_static("*"),
         }
     }
diff --git a/src/common/access_control_expose_headers.rs b/src/common/access_control_expose_headers.rs
index a9b7a50f..299087a2 100644
--- a/src/common/access_control_expose_headers.rs
+++ b/src/common/access_control_expose_headers.rs
@@ -42,7 +42,7 @@ derive_header! {
 
 impl AccessControlExposeHeaders {
     /// Returns an iterator over `HeaderName`s contained within.
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = HeaderName> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = HeaderName> + '_ {
         self.0.iter().filter_map(|s| s.parse().ok())
     }
 }
diff --git a/src/common/access_control_request_headers.rs b/src/common/access_control_request_headers.rs
index 5628d9d5..2f2ef061 100644
--- a/src/common/access_control_request_headers.rs
+++ b/src/common/access_control_request_headers.rs
@@ -43,7 +43,7 @@ derive_header! {
 
 impl AccessControlRequestHeaders {
     /// Returns an iterator over `HeaderName`s contained within.
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = HeaderName> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = HeaderName> + '_ {
         self.0.iter().filter_map(|s| s.parse().ok())
     }
 }
diff --git a/src/common/allow.rs b/src/common/allow.rs
index 0285d3c7..9a575972 100644
--- a/src/common/allow.rs
+++ b/src/common/allow.rs
@@ -44,7 +44,7 @@ derive_header! {
 
 impl Allow {
     /// Returns an iterator over `Method`s contained within.
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = Method> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = Method> + '_ {
         self.0.iter().filter_map(|s| s.parse().ok())
     }
 }
diff --git a/src/common/authorization.rs b/src/common/authorization.rs
index bb2c35ec..cd528a8c 100644
--- a/src/common/authorization.rs
+++ b/src/common/authorization.rs
@@ -63,7 +63,7 @@ impl Authorization<Bearer> {
     pub fn bearer(token: &str) -> Result<Self, InvalidBearerToken> {
         HeaderValueString::from_string(format!("Bearer {}", token))
             .map(|val| Authorization(Bearer(val)))
-            .ok_or_else(|| InvalidBearerToken { _inner: () })
+            .ok_or(InvalidBearerToken { _inner: () })
     }
 
     /// View the token part as a `&str`.
diff --git a/src/common/cache_control.rs b/src/common/cache_control.rs
index 7d5db055..9a612653 100644
--- a/src/common/cache_control.rs
+++ b/src/common/cache_control.rs
@@ -284,16 +284,16 @@ impl FromIterator<KnownDirective> for FromIter {
                     cc.flags.insert(Flags::PROXY_REVALIDATE);
                 }
                 Directive::MaxAge(secs) => {
-                    cc.max_age = Some(Duration::from_secs(secs.into()).into());
+                    cc.max_age = Some(Duration::from_secs(secs).into());
                 }
                 Directive::MaxStale(secs) => {
-                    cc.max_stale = Some(Duration::from_secs(secs.into()).into());
+                    cc.max_stale = Some(Duration::from_secs(secs).into());
                 }
                 Directive::MinFresh(secs) => {
-                    cc.min_fresh = Some(Duration::from_secs(secs.into()).into());
+                    cc.min_fresh = Some(Duration::from_secs(secs).into());
                 }
                 Directive::SMaxAge(secs) => {
-                    cc.s_max_age = Some(Duration::from_secs(secs.into()).into());
+                    cc.s_max_age = Some(Duration::from_secs(secs).into());
                 }
             }
         }
@@ -420,7 +420,7 @@ impl FromStr for KnownDirective {
             "" => return Err(()),
             _ => match s.find('=') {
                 Some(idx) if idx + 1 < s.len() => {
-                    match (&s[..idx], (&s[idx + 1..]).trim_matches('"')) {
+                    match (&s[..idx], (s[idx + 1..]).trim_matches('"')) {
                         ("max-age", secs) => secs.parse().map(Directive::MaxAge).map_err(|_| ())?,
                         ("max-stale", secs) => {
                             secs.parse().map(Directive::MaxStale).map_err(|_| ())?
diff --git a/src/common/connection.rs b/src/common/connection.rs
index 00299e47..ff562a35 100644
--- a/src/common/connection.rs
+++ b/src/common/connection.rs
@@ -87,10 +87,7 @@ impl Connection {
     /// ```
     pub fn contains(&self, name: impl AsConnectionOption) -> bool {
         let s = name.as_connection_option();
-        self.0
-            .iter()
-            .find(|&opt| opt.eq_ignore_ascii_case(s))
-            .is_some()
+        self.0.iter().any(|opt| opt.eq_ignore_ascii_case(s))
     }
 }
 
@@ -112,7 +109,7 @@ mod sealed {
 
     impl<'a> AsConnectionOption for &'a str {
         fn as_connection_option(&self) -> &str {
-            *self
+            self
         }
     }
 
diff --git a/src/common/content_encoding.rs b/src/common/content_encoding.rs
index cee95fcd..83bee36b 100644
--- a/src/common/content_encoding.rs
+++ b/src/common/content_encoding.rs
@@ -72,7 +72,7 @@ impl ContentEncoding {
     /// ```
     pub fn contains(&self, coding: impl AsCoding) -> bool {
         let s = coding.as_coding();
-        self.0.iter().find(|&opt| opt == s).is_some()
+        self.0.iter().any(|opt| opt == s)
     }
 }
 
@@ -87,7 +87,7 @@ mod sealed {
 
     impl<'a> Sealed for &'a str {
         fn as_coding(&self) -> &str {
-            *self
+            self
         }
     }
 }
diff --git a/src/common/content_type.rs b/src/common/content_type.rs
index 1ae15c2e..5d03362f 100644
--- a/src/common/content_type.rs
+++ b/src/common/content_type.rs
@@ -1,6 +1,6 @@
 use std::fmt;
 
-use mime::{self, Mime};
+use mime::Mime;
 
 /// `Content-Type` header, defined in
 /// [RFC7231](http://tools.ietf.org/html/rfc7231#section-3.1.1.5)
diff --git a/src/common/etag.rs b/src/common/etag.rs
index 25846b76..a43633b1 100644
--- a/src/common/etag.rs
+++ b/src/common/etag.rs
@@ -54,7 +54,7 @@ impl FromStr for ETag {
 
         EntityTag::from_owned(val)
             .map(ETag)
-            .ok_or_else(|| InvalidETag { _inner: () })
+            .ok_or(InvalidETag { _inner: () })
     }
 }
 
diff --git a/src/common/origin.rs b/src/common/origin.rs
index 6d4a022e..059c6f96 100644
--- a/src/common/origin.rs
+++ b/src/common/origin.rs
@@ -46,10 +46,7 @@ impl Origin {
     /// Checks if `Origin` is `null`.
     #[inline]
     pub fn is_null(&self) -> bool {
-        match self.0 {
-            OriginOrNull::Null => true,
-            _ => false,
-        }
+        matches!(self.0, OriginOrNull::Null)
     }
 
     /// Get the "scheme" part of this origin.
@@ -101,7 +98,7 @@ impl Origin {
         HeaderValue::from_maybe_shared(bytes)
             .ok()
             .and_then(|val| Self::try_from_value(&val))
-            .ok_or_else(|| InvalidOrigin { _inner: () })
+            .ok_or(InvalidOrigin { _inner: () })
     }
 
     // Used in AccessControlAllowOrigin
@@ -109,7 +106,7 @@ impl Origin {
         OriginOrNull::try_from_value(value).map(Origin)
     }
 
-    pub(super) fn into_value(&self) -> HeaderValue {
+    pub(super) fn to_value(&self) -> HeaderValue {
         (&self.0).into()
     }
 }
diff --git a/src/common/range.rs b/src/common/range.rs
index 6d35936d..edf97b61 100644
--- a/src/common/range.rs
+++ b/src/common/range.rs
@@ -10,7 +10,7 @@ use std::ops::{Bound, RangeBounds};
 /// # ABNF
 ///
 /// ```text
-/// Range =	byte-ranges-specifier / other-ranges-specifier
+/// Range = byte-ranges-specifier / other-ranges-specifier
 /// other-ranges-specifier = other-range-unit "=" other-range-set
 /// other-range-set = 1*VCHAR
 ///
@@ -66,10 +66,10 @@ impl Range {
     ///
     /// The length of the content is passed as an argument, and all ranges
     /// that can be satisfied will be iterated.
-    pub fn satisfiable_ranges<'a>(
-        &'a self,
+    pub fn satisfiable_ranges(
+        &self,
         len: u64,
-    ) -> impl Iterator<Item = (Bound<u64>, Bound<u64>)> + 'a {
+    ) -> impl Iterator<Item = (Bound<u64>, Bound<u64>)> + '_ {
         let s = self
             .0
             .to_str()
diff --git a/src/common/sec_websocket_accept.rs b/src/common/sec_websocket_accept.rs
index 89ec7c07..9b08e862 100644
--- a/src/common/sec_websocket_accept.rs
+++ b/src/common/sec_websocket_accept.rs
@@ -40,7 +40,7 @@ fn sign(key: &[u8]) -> SecWebsocketAccept {
     let mut sha1 = Sha1::default();
     sha1.update(key);
     sha1.update(&b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"[..]);
-    let b64 = Bytes::from(ENGINE.encode(&sha1.finalize()));
+    let b64 = Bytes::from(ENGINE.encode(sha1.finalize()));
 
     let val = ::HeaderValue::from_maybe_shared(b64).expect("base64 is a valid value");
 
diff --git a/src/common/strict_transport_security.rs b/src/common/strict_transport_security.rs
index 628b8004..ff8d3b6a 100644
--- a/src/common/strict_transport_security.rs
+++ b/src/common/strict_transport_security.rs
@@ -111,13 +111,13 @@ fn from_str(s: &str) -> Result<StrictTransportSecurity, ::Error> {
                 }
             }
         })
-        .fold(Some((None, None)), |res, dir| match (res, dir) {
-            (Some((None, sub)), Some(Directive::MaxAge(age))) => Some((Some(age), sub)),
-            (Some((age, None)), Some(Directive::IncludeSubdomains)) => Some((age, Some(()))),
-            (Some((Some(_), _)), Some(Directive::MaxAge(_)))
-            | (Some((_, Some(_))), Some(Directive::IncludeSubdomains))
+        .try_fold((None, None), |res, dir| match (res, dir) {
+            ((None, sub), Some(Directive::MaxAge(age))) => Some((Some(age), sub)),
+            ((age, None), Some(Directive::IncludeSubdomains)) => Some((age, Some(()))),
+            ((Some(_), _), Some(Directive::MaxAge(_)))
+            | ((_, Some(_)), Some(Directive::IncludeSubdomains))
             | (_, None) => None,
-            (res, _) => res,
+            (res, _) => Some(res),
         })
         .and_then(|res| match res {
             (Some(age), sub) => Some(StrictTransportSecurity {
diff --git a/src/map_ext.rs b/src/map_ext.rs
index e80ccda9..c79e59e0 100644
--- a/src/map_ext.rs
+++ b/src/map_ext.rs
@@ -1,5 +1,4 @@
 use super::{Error, Header, HeaderValue};
-use http;
 
 /// An extension trait adding "typed" methods to `http::HeaderMap`.
 pub trait HeaderMapExt: self::sealed::Sealed {
diff --git a/src/util/entity.rs b/src/util/entity.rs
index 67604be4..c1bda545 100644
--- a/src/util/entity.rs
+++ b/src/util/entity.rs
@@ -213,7 +213,7 @@ fn check_slice_validity(slice: &[u8]) -> bool {
         // The debug_assert is just in case we use check_slice_validity in
         // some new context that didnt come from a HeaderValue.
         debug_assert!(
-            (c >= b'\x21' && c <= b'\x7e') | (c >= b'\x80'),
+            (b'\x21'..=b'\x7e').contains(&c) | (c >= b'\x80'),
             "EntityTag expects HeaderValue to have check for control characters"
         );
         c != b'"'
diff --git a/src/util/flat_csv.rs b/src/util/flat_csv.rs
index 7be56c87..1589ebfe 100644
--- a/src/util/flat_csv.rs
+++ b/src/util/flat_csv.rs
@@ -40,6 +40,7 @@ impl<Sep: Separator> FlatCsv<Sep> {
             let mut in_quotes = false;
             value_str
                 .split(move |c| {
+                    #[allow(clippy::collapsible_else_if)]
                     if in_quotes {
                         if c == '"' {
                             in_quotes = false;
@@ -113,7 +114,7 @@ impl<'a, Sep: Separator> FromIterator<&'a HeaderValue> for FlatCsv<Sep> {
             .next()
             .cloned()
             .map(|val| BytesMut::from(val.as_bytes()))
-            .unwrap_or_else(|| BytesMut::new());
+            .unwrap_or_default();
 
         for val in values {
             buf.extend_from_slice(&[Sep::BYTE, b' ']);
@@ -144,7 +145,7 @@ impl<Sep: Separator> FromIterator<HeaderValue> for FlatCsv<Sep> {
         let mut buf = values
             .next()
             .map(|val| BytesMut::from(val.as_bytes()))
-            .unwrap_or_else(|| BytesMut::new());
+            .unwrap_or_default();
 
         for val in values {
             buf.extend_from_slice(&[Sep::BYTE, b' ']);
diff --git a/src/util/http_date.rs b/src/util/http_date.rs
index da3f8396..ec58410f 100644
--- a/src/util/http_date.rs
+++ b/src/util/http_date.rs
@@ -4,7 +4,6 @@ use std::time::SystemTime;
 
 use bytes::Bytes;
 use http::header::HeaderValue;
-use httpdate;
 
 use super::IterExt;
 
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 07fddbfb..0a58fce3 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -82,6 +82,6 @@ impl TryFromValues for HeaderValue {
     where
         I: Iterator<Item = &'i HeaderValue>,
     {
-        values.next().cloned().ok_or_else(|| ::Error::invalid())
+        values.next().cloned().ok_or_else(::Error::invalid)
     }
 }