diff --git a/include/proto/ssl_sock.h b/include/proto/ssl_sock.h
index 91456e2..d43ad69 100644
--- a/include/proto/ssl_sock.h
+++ b/include/proto/ssl_sock.h
@@ -50,6 +50,7 @@
 void ssl_sock_free_all_ctx(struct bind_conf *bind_conf);
 int ssl_sock_load_ca(struct bind_conf *bind_conf);
 void ssl_sock_free_ca(struct bind_conf *bind_conf);
+const char *ssl_sock_get_cert_sig(struct connection *conn);
 const char *ssl_sock_get_cipher_name(struct connection *conn);
 const char *ssl_sock_get_proto_version(struct connection *conn);
 void ssl_sock_set_servername(struct connection *conn, const char *hostname);