diff --git a/utils/nfnl_osf.c b/utils/nfnl_osf.c
index 15d5319..922d90a 100644
--- a/utils/nfnl_osf.c
+++ b/utils/nfnl_osf.c
@@ -378,9 +378,11 @@ static int osf_load_line(char *buffer, int len, int del)
 	memset(buf, 0, sizeof(buf));
 
 	if (del)
-		nfnl_fill_hdr(nfnlssh, nmh, 0, AF_UNSPEC, 0, OSF_MSG_REMOVE, NLM_F_REQUEST);
+		nfnl_fill_hdr(nfnlssh, nmh, 0, AF_UNSPEC, 0, OSF_MSG_REMOVE,
+			      NLM_F_ACK | NLM_F_REQUEST);
 	else
-		nfnl_fill_hdr(nfnlssh, nmh, 0, AF_UNSPEC, 0, OSF_MSG_ADD, NLM_F_REQUEST | NLM_F_CREATE);
+		nfnl_fill_hdr(nfnlssh, nmh, 0, AF_UNSPEC, 0, OSF_MSG_ADD,
+			      NLM_F_ACK | NLM_F_REQUEST | NLM_F_CREATE);
 
 	nfnl_addattr_l(nmh, sizeof(buf), OSF_ATTR_FINGER, &f, sizeof(struct xt_osf_user_finger));