diff --git a/src/client.c b/src/client.c
index b3e52c3..f27f606 100644
--- a/src/client.c
+++ b/src/client.c
@@ -397,7 +397,6 @@ send_next_frag(int fd)
 
 	/* Get next fragment to send */
 	f = window_get_next_sending_fragment(outbuf, next_downstream_ack);
-	window_tick(outbuf);
 	if (f == NULL) {
 		if (is_sending()) {
 			/* There is stuff to send but we're out of sync, so send a ping
@@ -433,6 +432,8 @@ send_next_frag(int fd)
 		datacmc = 0;
 
 	send_query(fd, (char *)buf);
+
+	window_tick(outbuf);
 }
 
 static void
diff --git a/src/user.c b/src/user.c
index 22a0132..bf95f53 100644
--- a/src/user.c
+++ b/src/user.c
@@ -135,12 +135,16 @@ find_available_user()
 	for (int u = 0; u < usercount; u++) {
 		/* Not used at all or not used in one minute */
 		if (!user_active(u)) {
+			struct tun_user *user = &users[u];
+			if (user->incoming) window_buffer_destroy(user->incoming);
+			if (user->outgoing) window_buffer_destroy(user->outgoing);
 			/* reset all stats */
-			memset(&users[u], 0, sizeof(users[u]));
-			users[u].active = 1;
-			users[u].last_pkt = time(NULL);
-			users[u].fragsize = MAX_FRAGSIZE;
-			users[u].conn = CONN_DNS_NULL;
+			user->active = 1;
+			user->authenticated = 0;
+			user->authenticated_raw = 0;
+			user->last_pkt = time(NULL);
+			user->fragsize = MAX_FRAGSIZE;
+			user->conn = CONN_DNS_NULL;
 			return u;
 		}
 	}
@@ -177,12 +181,7 @@ check_user_and_ip(int userid, struct query *q)
 	if (userid < 0 || userid >= created_users ) {
 		return 1;
 	}
-	if (!users[userid].active || users[userid].disabled) {
-		return 1;
-	}
-	if (users[userid].last_pkt + 60 < time(NULL)) {
-		return 1;
-	}
+	if (!user_active(userid)) return 1;
 
 	/* return early if IP checking is disabled */
 	if (!check_ip) {
diff --git a/src/window.c b/src/window.c
index c29a5b5..45bc2fd 100644
--- a/src/window.c
+++ b/src/window.c
@@ -56,7 +56,8 @@ window_buffer_init(size_t length, unsigned windowsize, unsigned fragsize, int di
 void
 window_buffer_destroy(struct frag_buffer *w)
 {
-	free(w->frags);
+	if (!w) return;
+	if (w->frags) free(w->frags);
 	free(w);
 }
 
@@ -120,7 +121,7 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, unsigned maxlen, in
 //		warnx("chunk_start pointing to non-start fragment (%u)!", w->frags[w->chunk_start].seqID);
 		return 0;
 	}
-	*compression = 1;
+	if (compression) *compression = 1;
 
 	fragment *f;
 	size_t i, curseq;
@@ -139,7 +140,7 @@ window_reassemble_data(struct frag_buffer *w, uint8_t *data, unsigned maxlen, in
 		memcpy(dest, f->data, MIN(fraglen, maxlen));
 		dest += fraglen;
 		datalen += fraglen;
-		*compression &= f->compressed & 1;
+		if (compression) *compression &= f->compressed & 1;
 		if (f->compressed != *compression) {
 			warnx("Inconsistent compression flags in chunk. Not reassembling!");
 			return 0;