diff --git a/core/lib/Cargo.toml b/core/lib/Cargo.toml
index acfaf267..f4a16469 100644
--- a/core/lib/Cargo.toml
+++ b/core/lib/Cargo.toml
@@ -33,8 +33,7 @@ num_cpus = "1.0"
 state = "0.4.1"
 time = "0.2.4"
 memchr = "2" # TODO: Use pear instead.
-base64 = "0.11"
-base16 = "0.2"
+binascii = "0.1"
 pear = "0.1"
 atty = "0.2"
 
diff --git a/core/lib/src/config/config.rs b/core/lib/src/config/config.rs
index ff05960e..01dea923 100644
--- a/core/lib/src/config/config.rs
+++ b/core/lib/src/config/config.rs
@@ -10,7 +10,6 @@ use crate::config::{Table, Value, Array, Datetime};
 use crate::http::private::Key;
 
 use super::custom_values::*;
-use {num_cpus, base16, base64};
 
 /// Structure for Rocket application configuration.
 ///
@@ -423,12 +422,12 @@ impl Config {
     }
 
     /// Sets the `secret_key` in `self` to `key` which must be a 256-bit base64
-    /// or base16 encoded string.
+    /// or base16 (hex) encoded string.
     ///
     /// # Errors
     ///
-    /// If `key` is not a valid 256-bit encoded string, returns a
-    /// `BadType` error.
+    /// If `key` is not a valid 256-bit encoded string, returns a `BadType`
+    /// error.
     ///
     /// # Example
     ///
@@ -436,33 +435,28 @@ impl Config {
     /// use rocket::config::{Config, Environment};
     ///
     /// let mut config = Config::new(Environment::Staging);
+    ///
+    /// // A base64 encoded key.
     /// let key = "8Xui8SN4mI+7egV/9dlfYYLGQJeEx4+DwmSQLwDVXJg=";
     /// assert!(config.set_secret_key(key).is_ok());
+    ///
+    /// // A base16 (hex) encoded key.
     /// let key = "fe4c5b09a9ac372156e44ce133bc940685ef5e0394d6e9274aadacc21e4f2643";
     /// assert!(config.set_secret_key(key).is_ok());
+    ///
+    /// // An invalid key.
     /// assert!(config.set_secret_key("hello? anyone there?").is_err());
     /// ```
     pub fn set_secret_key<K: Into<String>>(&mut self, key: K) -> Result<()> {
         let key = key.into();
-        let error = self.bad_type("secret_key", "string",
-                                  "a 256-bit base16 or base64 encoded string");
+        let e = self.bad_type("secret_key", "string", "a 256-bit base64 or hex encoded string");
 
+        // `binascii` requires a bit more space than actual output for padding
+        let mut bytes = [0u8; 36];
         let bytes = match key.len() {
-            44 => {
-                match base64::decode(&key) {
-                    Ok(bytes) => bytes,
-                    Err(_) => return Err(error)
-                }
-            }
-            64 => {
-                match base16::decode(&key) {
-                    Ok(bytes) => bytes,
-                    Err(_) => return Err(error)
-                }
-            }
-            _ => {
-                return Err(error)
-            }
+            44 => binascii::b64decode(key.as_bytes(), &mut bytes).map_err(|_| e)?,
+            64 => binascii::hex2bin(key.as_bytes(), &mut bytes).map_err(|_| e)?,
+            _ => return Err(e)
         };
 
         self.secret_key = SecretKey::Provided(Key::from_master(&bytes));