diff --git a/src/net/tcp/http.c b/src/net/tcp/http.c
index 90c117d5..01f0aeac 100644
--- a/src/net/tcp/http.c
+++ b/src/net/tcp/http.c
@@ -71,7 +71,7 @@ static void http_connected ( struct tcp_connection *conn ) {
  * @v conn	a TCP Connection
  * @v len	the length of data acked
  */
-static void http_acked ( struct tcp_connection *conn, size_t len ) {
+static void http_acked ( struct tcp_connection *conn, size_t len __attribute__ ((unused)) ) {
 	struct http_request *http = tcp_to_http ( conn );
 
 	// assume that the whole GET request was sent in on epacket