diff --git a/src/OpenSSL/SSL.py b/src/OpenSSL/SSL.py
index ffb1998..10116ed 100644
--- a/src/OpenSSL/SSL.py
+++ b/src/OpenSSL/SSL.py
@@ -823,7 +823,7 @@
             raise TypeError("cipher_list must be a byte string.")
 
         _openssl_assert(
-            _lib.SSL_CTX_set_cipher_list(self._context, cipher_list)
+            _lib.SSL_CTX_set_cipher_list(self._context, cipher_list) == 1
         )
 
     def set_client_ca_list(self, certificate_authorities):