diff --git a/.travis.yml b/.travis.yml
index d32bf418..583403c8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,9 @@ sudo: false
 
 cache: cargo
 
+env: # important!
+  global: RUSTFLAGS=-Dwarnings
+
 matrix:
   include:
     - rust: stable
diff --git a/src/error.rs b/src/error.rs
index 3b31a103..5d480272 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -66,6 +66,7 @@ impl Error {
 }
 
 impl error::Error for Error {
+    #[allow(deprecated)]
     fn description(&self) -> &str {
         use self::ErrorKind::*;
 
diff --git a/src/header/name.rs b/src/header/name.rs
index 8e871ecf..87b5a195 100644
--- a/src/header/name.rs
+++ b/src/header/name.rs
@@ -2002,6 +2002,7 @@ impl fmt::Debug for InvalidHeaderName {
 }
 
 impl fmt::Display for InvalidHeaderName {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.description().fmt(f)
     }
diff --git a/src/header/value.rs b/src/header/value.rs
index c3096a15..7b79224c 100644
--- a/src/header/value.rs
+++ b/src/header/value.rs
@@ -568,6 +568,7 @@ impl fmt::Debug for InvalidHeaderValue {
 }
 
 impl fmt::Display for InvalidHeaderValue {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.description().fmt(f)
     }
@@ -580,6 +581,7 @@ impl Error for InvalidHeaderValue {
 }
 
 impl fmt::Display for ToStrError {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.description().fmt(f)
     }
diff --git a/src/lib.rs b/src/lib.rs
index c5a43699..b3989d41 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -158,7 +158,7 @@
 //! assert_eq!(uri.query(), None);
 //! ```
 
-#![deny(warnings, missing_docs, missing_debug_implementations)]
+#![warn(missing_docs, missing_debug_implementations)]
 
 #[cfg(test)]
 #[macro_use]
diff --git a/src/method.rs b/src/method.rs
index 6a8ed142..67e51632 100644
--- a/src/method.rs
+++ b/src/method.rs
@@ -364,6 +364,7 @@ impl fmt::Debug for InvalidMethod {
 }
 
 impl fmt::Display for InvalidMethod {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}", self.description())
     }
diff --git a/src/status.rs b/src/status.rs
index 5b4c41f2..f6121444 100644
--- a/src/status.rs
+++ b/src/status.rs
@@ -514,6 +514,7 @@ impl fmt::Debug for InvalidStatusCode {
 }
 
 impl fmt::Display for InvalidStatusCode {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(self.description())
     }
diff --git a/src/uri/mod.rs b/src/uri/mod.rs
index 066a966b..4319ad35 100644
--- a/src/uri/mod.rs
+++ b/src/uri/mod.rs
@@ -1026,6 +1026,7 @@ impl From<ErrorKind> for InvalidUriParts {
 }
 
 impl fmt::Display for InvalidUri {
+    #[allow(deprecated)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.description().fmt(f)
     }
@@ -1056,6 +1057,7 @@ impl fmt::Display for InvalidUriParts {
 }
 
 impl Error for InvalidUriParts {
+    #[allow(deprecated)]
     fn description(&self) -> &str {
         self.0.description()
     }