diff --git a/session.c b/session.c
index 462db7c7f..02d20e60e 100644
--- a/session.c
+++ b/session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.108 2026/09/21 12:43:36 nicm Exp $ */
+/* $OpenBSD: session.c,v 1.109 2026/09/25 08:46:06 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -747,14 +747,21 @@ session_renumber_windows(struct session *s)
 	struct winlink		*wl, *wl1, *wl_new;
 	struct winlinks		 old_wins;
 	struct winlink_stack	 old_lastw;
+	u_int			 n;
 	int			 new_idx, new_curw_idx, marked_idx = -1;
 
+	/* Start renumbering from the base-index if it's set. */
+	new_idx = options_get_number(s->options, "base-index");
+
+	/* Leave the indexes alone if they do not all fit from there. */
+	n = winlink_count(&s->windows);
+	if (n > (u_int)INT_MAX - (u_int)new_idx + 1)
+		return;
+
 	/* Save and replace old window list. */
 	memcpy(&old_wins, &s->windows, sizeof old_wins);
 	RB_INIT(&s->windows);
 
-	/* Start renumbering from the base-index if it's set. */
-	new_idx = options_get_number(s->options, "base-index");
 	new_curw_idx = 0;
 
 	/* Go through the winlinks and assign new indexes. */
@@ -769,7 +776,8 @@ session_renumber_windows(struct session *s)
 		if (wl == s->curw)
 			new_curw_idx = wl_new->idx;
 
-		new_idx++;
+		if (RB_NEXT(winlinks, &old_wins, wl) != NULL)
+			new_idx++;
 	}
 
 	/* Fix the stack of last windows now. */
diff --git a/tmux.c b/tmux.c
index ab7c5133a..51b0c29eb 100644
--- a/tmux.c
+++ b/tmux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.c,v 1.223 2026/08/17 14:47:41 nicm Exp $ */
+/* $OpenBSD: tmux.c,v 1.224 2026/09/25 09:11:18 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -178,8 +178,8 @@ expand_paths(const char *s, char ***paths, u_int *n, int no_realpath)
 			path = expanded;
 		else {
 			if (realpath(expanded, resolved) == NULL) {
-				log_debug("%s: realpath(\"%s\") failed: %s", __func__,
-			  expanded, strerror(errno));
+				log_debug("%s: realpath(\"%s\") failed: %s",
+				    __func__, expanded, strerror(errno));
 				free(expanded);
 				continue;
 			}
diff --git a/window.c b/window.c
index f86e8470f..777788862 100644
--- a/window.c
+++ b/window.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: window.c,v 1.378 2026/09/24 11:19:39 nicm Exp $ */
+/* $OpenBSD: window.c,v 1.379 2026/09/25 08:46:06 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -2436,7 +2436,7 @@ winlink_shuffle_up(struct session *s, struct winlink *wl, int before)
 {
 	int	 idx, last;
 
-	if (wl == NULL)
+	if (wl == NULL || wl->idx == INT_MAX)
 		return (-1);
 	if (before)
 		idx = wl->idx;