Fix nid.py comment style
diff --git a/cryptography/hazmat/bindings/openssl/nid.py b/cryptography/hazmat/bindings/openssl/nid.py
index ea6fd4d..7fa0866 100644
--- a/cryptography/hazmat/bindings/openssl/nid.py
+++ b/cryptography/hazmat/bindings/openssl/nid.py
@@ -193,7 +193,7 @@
 """
 
 CUSTOMIZATIONS = """
-// OpenSSL 0.9.8g+
+/* OpenSSL 0.9.8g+ */
 #if OPENSSL_VERSION_NUMBER >= 0x0090807fL
 static const long Cryptography_HAS_ECDSA_SHA2_NIDS = 1;
 #else