diff --git a/src/cryptography/hazmat/bindings/openssl/ssl.py b/src/cryptography/hazmat/bindings/openssl/ssl.py
index 91ae36a..bf62713 100644
--- a/src/cryptography/hazmat/bindings/openssl/ssl.py
+++ b/src/cryptography/hazmat/bindings/openssl/ssl.py
@@ -302,6 +302,7 @@
 long SSL_CTX_get_timeout(const SSL_CTX *);
 
 const SSL_CIPHER *SSL_get_current_cipher(const SSL *);
+int SSL_version(const SSL *);
 
 /* SNI APIs were introduced in OpenSSL 1.0.0.  To continue to support
  * earlier versions some special handling of these is necessary.