diff --git a/openssl/src/crypto/symm.rs b/openssl/src/crypto/symm.rs
index cb3cb55b..a1736804 100644
--- a/openssl/src/crypto/symm.rs
+++ b/openssl/src/crypto/symm.rs
@@ -1,4 +1,5 @@
 use std::iter::repeat;
+use std::convert::AsRef;
 use libc::{c_int};
 
 use ffi;
@@ -86,7 +87,7 @@ impl Crypter {
     /**
      * Initializes this crypter.
      */
-    pub fn init(&self, mode: Mode, key: &[u8], iv: &[u8]) {
+    pub fn init<T: AsRef<[u8]>>(&self, mode: Mode, key: &[u8], iv: T) {
         unsafe {
             let mode = match mode {
                 Mode::Encrypt => 1 as c_int,
@@ -98,7 +99,7 @@ impl Crypter {
                 self.ctx,
                 self.evp,
                 key.as_ptr(),
-                iv.as_ptr(),
+                iv.as_ref().as_ptr(),
                 mode
             );
         }
@@ -157,7 +158,7 @@ impl Drop for Crypter {
  * Encrypts data, using the specified crypter type in encrypt mode with the
  * specified key and iv; returns the resulting (encrypted) data.
  */
-pub fn encrypt(t: Type, key: &[u8], iv: &[u8], data: &[u8]) -> Vec<u8> {
+pub fn encrypt<T: AsRef<[u8]>>(t: Type, key: &[u8], iv: T, data: &[u8]) -> Vec<u8> {
     let c = Crypter::new(t);
     c.init(Mode::Encrypt, key, iv);
     let mut r = c.update(data);
@@ -170,7 +171,7 @@ pub fn encrypt(t: Type, key: &[u8], iv: &[u8], data: &[u8]) -> Vec<u8> {
  * Decrypts data, using the specified crypter type in decrypt mode with the
  * specified key and iv; returns the resulting (decrypted) data.
  */
-pub fn decrypt(t: Type, key: &[u8], iv: &[u8], data: &[u8]) -> Vec<u8> {
+pub fn decrypt<T: AsRef<[u8]>>(t: Type, key: &[u8], iv: T, data: &[u8]) -> Vec<u8> {
     let c = Crypter::new(t);
     c.init(Mode::Decrypt, key, iv);
     let mut r = c.update(data);