diff --git a/lib/security.c b/lib/security.c
index 699be47a3..d0eccdf7f 100644
--- a/lib/security.c
+++ b/lib/security.c
@@ -336,12 +336,14 @@ static ssize_t sec_write(struct connectdata *conn, int fd,
   return tx;
 }
 
-int
-Curl_sec_fflush_fd(struct connectdata *conn, int fd)
+/* FIXME: fd should be a curl_socket_t */
+int Curl_sec_fflush_fd(struct connectdata *conn, int fd)
 {
-  if(conn->data_prot != prot_clear) {
-    do_sec_send(conn, fd, NULL, 0);
-  }
+  if(conn->data_prot == prot_clear)
+    return 0;
+
+  /* Force a flush by trying to send no data */
+  do_sec_send(conn, fd, NULL, 0);
   return 0;
 }