diff --git a/openssl-sys/src/ssl.rs b/openssl-sys/src/ssl.rs
index 52ea5b2135..d0f760e64b 100644
--- a/openssl-sys/src/ssl.rs
+++ b/openssl-sys/src/ssl.rs
@@ -241,10 +241,28 @@ pub const SSL_MODE_SEND_CLIENTHELLO_TIME: c_long = 0x20;
 pub const SSL_MODE_SEND_SERVERHELLO_TIME: c_long = 0x40;
 #[cfg(ossl101)]
 pub const SSL_MODE_SEND_FALLBACK_SCSV: c_long = 0x80;
+#[cfg(ossl110)]
+pub const SSL_MODE_ASYNC: c_long = 0x100;
 
 pub unsafe fn SSL_CTX_set_mode(ctx: *mut SSL_CTX, op: c_long) -> c_long {
     SSL_CTX_ctrl(ctx, SSL_CTRL_MODE, op, ptr::null_mut())
 }
+pub unsafe fn SSL_CTX_clear_mode(ctx: *mut SSL_CTX, op: c_long) -> c_long {
+    SSL_CTX_ctrl(ctx, SSL_CTRL_CLEAR_MODE, op, ptr::null_mut())
+}
+pub unsafe fn SSL_CTX_get_mode(ctx: *mut SSL_CTX) -> c_long {
+    SSL_CTX_ctrl(ctx, SSL_CTRL_MODE, 0, ptr::null_mut())
+}
+
+pub unsafe fn SSL_set_mode(ssl: *mut SSL, op: c_long) -> c_long {
+    SSL_ctrl(ssl, SSL_CTRL_MODE, op, ptr::null_mut())
+}
+pub unsafe fn SSL_clear_mode(ssl: *mut SSL, op: c_long) -> c_long {
+    SSL_ctrl(ssl, SSL_CTRL_CLEAR_MODE, op, ptr::null_mut())
+}
+pub unsafe fn SSL_get_mode(ssl: *mut SSL) -> c_long {
+    SSL_ctrl(ssl, SSL_CTRL_MODE, 0, ptr::null_mut())
+}
 
 #[cfg(ossl111)]
 pub const SSL_COOKIE_LENGTH: c_int = 4096;
@@ -338,6 +356,7 @@ pub const SSL_CTRL_GET_TLSEXT_STATUS_REQ_OCSP_RESP: c_int = 70;
 pub const SSL_CTRL_SET_TLSEXT_STATUS_REQ_OCSP_RESP: c_int = 71;
 #[cfg(any(libressl, all(ossl101, not(ossl110))))]
 pub const SSL_CTRL_CLEAR_OPTIONS: c_int = 77;
+pub const SSL_CTRL_CLEAR_MODE: c_int = 78;
 pub const SSL_CTRL_GET_EXTRA_CHAIN_CERTS: c_int = 82;
 #[cfg(ossl102)]
 pub const SSL_CTRL_CHAIN_CERT: c_int = 89;
diff --git a/openssl/src/ssl/mod.rs b/openssl/src/ssl/mod.rs
index fe1e38649f..4a97063963 100644
--- a/openssl/src/ssl/mod.rs
+++ b/openssl/src/ssl/mod.rs
@@ -332,6 +332,15 @@ bitflags! {
         /// Do not use this unless you know what you're doing!
         #[cfg(not(libressl))]
         const SEND_FALLBACK_SCSV = ffi::SSL_MODE_SEND_FALLBACK_SCSV;
+
+        /// Enable asynchronous processing.
+        ///
+        /// TLS I/O operations may indicate a retry with SSL_ERROR_WANT_ASYNC with this mode set
+        /// if an asynchronous capable engine is used to perform cryptographic operations.
+        ///
+        /// Do not use this unless you know what you're doing!
+        #[cfg(ossl110)]
+        const ASYNC = ffi::SSL_MODE_ASYNC;
     }
 }
 
@@ -675,11 +684,13 @@ cfg_if! {
         type SslCacheTy = i64;
         type SslCacheSize = libc::c_ulong;
         type MtuTy = u32;
+        type ModeTy = u32;
         type SizeTy = usize;
     } else {
         type SslCacheTy = i64;
         type SslCacheSize = c_long;
         type MtuTy = c_long;
+        type ModeTy = c_long;
         type SizeTy = u32;
     }
 }
@@ -847,11 +858,31 @@ impl SslContextBuilder {
         }
     }
 
-    /// Sets the mode used by the context, returning the previous mode.
+    /// Sets the bit mask in mode to the mode set used by the context, returning the new mode bit mask.
+    ///
+    /// Options already set before are not cleared.
     #[corresponds(SSL_CTX_set_mode)]
     pub fn set_mode(&mut self, mode: SslMode) -> SslMode {
         unsafe {
-            let bits = ffi::SSL_CTX_set_mode(self.as_ptr(), mode.bits() as MtuTy) as SslBitType;
+            let bits = ffi::SSL_CTX_set_mode(self.as_ptr(), mode.bits() as ModeTy) as SslBitType;
+            SslMode::from_bits_retain(bits)
+        }
+    }
+
+    /// Clear the bit mask in mode to the mode set used by the context, returning the new mode bit mask.
+    #[corresponds(SSL_CTX_clear_mode)]
+    pub fn clear_mode(&mut self, mode: SslMode) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_CTX_clear_mode(self.as_ptr(), mode.bits() as ModeTy) as SslBitType;
+            SslMode::from_bits_retain(bits)
+        }
+    }
+
+    /// Returns the mode set for the context.
+    #[corresponds(SSL_CTX_get_mode)]
+    pub fn mode(&self) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_CTX_get_mode(self.as_ptr()) as SslBitType;
             SslMode::from_bits_retain(bits)
         }
     }
@@ -2370,6 +2401,35 @@ impl SslRef {
         unsafe { ErrorCode::from_raw(ffi::SSL_get_error(self.as_ptr(), ret)) }
     }
 
+    /// Sets the bit mask in mode to the mode set used by the SSL, returning the new mode bit mask.
+    ///
+    /// Options already set before are not cleared.
+    #[corresponds(SSL_set_mode)]
+    pub fn set_mode(&mut self, mode: SslMode) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_set_mode(self.as_ptr(), mode.bits() as ModeTy) as SslBitType;
+            SslMode::from_bits_retain(bits)
+        }
+    }
+
+    /// Clear the bit mask in mode to the mode set used by the SSL, returning the new mode bit mask.
+    #[corresponds(SSL_clear_mode)]
+    pub fn clear_mode(&mut self, mode: SslMode) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_clear_mode(self.as_ptr(), mode.bits() as ModeTy) as SslBitType;
+            SslMode::from_bits_retain(bits)
+        }
+    }
+
+    /// Returns the mode set for the SSL.
+    #[corresponds(SSL_get_mode)]
+    pub fn mode(&self) -> SslMode {
+        unsafe {
+            let bits = ffi::SSL_get_mode(self.as_ptr()) as SslBitType;
+            SslMode::from_bits_retain(bits)
+        }
+    }
+
     /// Configure as an outgoing stream from a client.
     #[corresponds(SSL_set_connect_state)]
     pub fn set_connect_state(&mut self) {