diff --git a/openssl/src/ssl/bio.rs b/openssl/src/ssl/bio.rs
index c5152a415bd9a99f8dce308f215278f9faf93c1d..4dc7cbd42f7c007778205cfc57b92464d97affc1 100644
--- a/openssl/src/ssl/bio.rs
+++ b/openssl/src/ssl/bio.rs
@@ -68,10 +68,10 @@ pub unsafe fn get_mut<'a, S: 'a>(bio: *mut BIO) -> &'a mut S {
 }
 
 unsafe fn state<'a, S: 'a>(bio: *mut BIO) -> &'a mut StreamState<S> {
-    mem::transmute(compat::BIO_get_data(bio))
+    &mut *(compat::BIO_get_data(bio) as *mut _)
 }
 
-unsafe extern "C" fn bwrite<S: Write>(bio: *mut BIO, buf: *const c_char, len: c_int) -> c_int {
+unsafe extern fn bwrite<S: Write>(bio: *mut BIO, buf: *const c_char, len: c_int) -> c_int {
     BIO_clear_retry_flags(bio);
 
     let state = state::<S>(bio);
@@ -93,7 +93,7 @@ unsafe extern "C" fn bwrite<S: Write>(bio: *mut BIO, buf: *const c_char, len: c_
     }
 }
 
-unsafe extern "C" fn bread<S: Read>(bio: *mut BIO, buf: *mut c_char, len: c_int) -> c_int {
+unsafe extern fn bread<S: Read>(bio: *mut BIO, buf: *mut c_char, len: c_int) -> c_int {
     BIO_clear_retry_flags(bio);
 
     let state = state::<S>(bio);
@@ -123,11 +123,11 @@ fn retriable_error(err: &io::Error) -> bool {
     }
 }
 
-unsafe extern "C" fn bputs<S: Write>(bio: *mut BIO, s: *const c_char) -> c_int {
+unsafe extern fn bputs<S: Write>(bio: *mut BIO, s: *const c_char) -> c_int {
     bwrite::<S>(bio, s, strlen(s) as c_int)
 }
 
-unsafe extern "C" fn ctrl<S: Write>(bio: *mut BIO,
+unsafe extern fn ctrl<S: Write>(bio: *mut BIO,
                                     cmd: c_int,
                                     _num: c_long,
                                     _ptr: *mut c_void)
@@ -151,7 +151,7 @@ unsafe extern "C" fn ctrl<S: Write>(bio: *mut BIO,
     }
 }
 
-unsafe extern "C" fn create(bio: *mut BIO) -> c_int {
+unsafe extern fn create(bio: *mut BIO) -> c_int {
     compat::BIO_set_init(bio, 0);
     compat::BIO_set_num(bio, 0);
     compat::BIO_set_data(bio, ptr::null_mut());
@@ -159,7 +159,7 @@ unsafe extern "C" fn create(bio: *mut BIO) -> c_int {
     1
 }
 
-unsafe extern "C" fn destroy<S>(bio: *mut BIO) -> c_int {
+unsafe extern fn destroy<S>(bio: *mut BIO) -> c_int {
     if bio.is_null() {
         return 0;
     }