diff --git a/Cargo.toml b/Cargo.toml
index 99e85eb..94350be 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,7 +15,7 @@ bytes = "0.4"
 encoding_rs = "0.8"
 futures = "0.1.23"
 http = "0.1.14"
-hyper = "0.12.13"
+hyper = "0.12.20"
 hyper-old-types = { version = "0.11", optional = true, features = ["compat"] }
 hyper-tls = { version = "0.3", optional = true }
 libflate = "0.1.18"
@@ -26,9 +26,10 @@ native-tls = { version = "0.2", optional = true }
 serde = "1.0"
 serde_json = "1.0"
 serde_urlencoded = "0.5"
-tokio = "0.1.7"
+tokio = { version = "0.1.7", default-features = false, features = ["rt-full"] }
 tokio-executor = "0.1.4" # a minimum version so trust-dns-resolver compiles
 tokio-io = "0.1"
+tokio-threadpool = "0.1.8" # a minimum version so tokio compiles
 tokio-timer = "0.2.6" # a minimum version so trust-dns-resolver compiles
 trust-dns-resolver = "0.10"
 url = "1.2"
diff --git a/src/tls.rs b/src/tls.rs
index 03dd676..2bf335e 100644
--- a/src/tls.rs
+++ b/src/tls.rs
@@ -4,7 +4,7 @@ use rustls::{TLSError, ServerCertVerifier, RootCertStore, ServerCertVerified};
 #[cfg(feature = "rustls-tls")]
 use tokio_rustls::webpki::DNSNameRef;
 
-/// Represent an X509 certificate.
+/// Represent a server X509 certificate.
 pub struct Certificate {
     pub(crate) inner: inner::Certificate
 }
@@ -45,10 +45,6 @@ impl Certificate {
     /// # Ok(())
     /// # }
     /// ```
-    ///
-    /// # Errors
-    ///
-    /// It never returns error.
     pub fn from_der(der: &[u8]) -> ::Result<Certificate> {
         Ok(Certificate {
             inner: inner::Certificate::Der(der.to_owned())
@@ -72,10 +68,6 @@ impl Certificate {
     /// # Ok(())
     /// # }
     /// ```
-    ///
-    /// # Errors
-    ///
-    /// It never returns error.
     pub fn from_pem(der: &[u8]) -> ::Result<Certificate> {
         Ok(Certificate {
             inner: inner::Certificate::Pem(der.to_owned())
@@ -111,10 +103,6 @@ impl Identity {
     /// # Ok(())
     /// # }
     /// ```
-    ///
-    /// # Errors
-    ///
-    /// It never returns error.
     #[cfg(feature = "default-tls")]
     pub fn from_pkcs12_der(der: &[u8], password: &str) -> ::Result<Identity> {
         Ok(Identity {
@@ -141,10 +129,6 @@ impl Identity {
     /// # Ok(())
     /// # }
     /// ```
-    ///
-    /// # Errors
-    ///
-    /// It never returns error.
     #[cfg(feature = "rustls-tls")]
     pub fn from_pem(pem: &[u8]) -> ::Result<Identity> {
         Ok(Identity {