add comments
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index e8b1f74..d99c7d9 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -1143,7 +1143,7 @@
 void SSL_CTX_set_cert_verify_callback(SSL_CTX *ctx,int (*cb)(),char *arg)
 	{
 	ctx->app_verify_callback=cb;
-	ctx->app_verify_arg=arg;
+	ctx->app_verify_arg=arg; /* never used */
 	}
 
 void SSL_CTX_set_verify(SSL_CTX *ctx,int mode,int (*cb)(int, X509_STORE_CTX *))