diff --git a/lib/ngtcp2_conn.c b/lib/ngtcp2_conn.c
index 45fbaa3fc13d5bca371f5e893c0b26f93b3d4b16..4c1dcbdc8f5d7af5a68efc54046bebe150f35b46 100644
--- a/lib/ngtcp2_conn.c
+++ b/lib/ngtcp2_conn.c
@@ -794,7 +794,7 @@ static ngtcp2_duration conn_compute_ack_delay(ngtcp2_conn *conn) {
   }
 
   return ngtcp2_min(initial_delay,
-                    (ngtcp2_duration)(conn->rcs.smoothed_rtt / 4));
+                    (ngtcp2_duration)(conn->rcs.smoothed_rtt / 8));
 }
 
 /*