diff --git a/cmd-queue.c b/cmd-queue.c
index 54163919..6dd5f9dd 100644
--- a/cmd-queue.c
+++ b/cmd-queue.c
@@ -269,6 +269,15 @@ cmdq_add_format(struct cmdq_state *state, const char *key, const char *fmt, ...)
 	free(value);
 }
 
+/* Add formats to command queue. */
+void
+cmdq_add_formats(struct cmdq_state *state, struct format_tree *ft)
+{
+	if (state->formats == NULL)
+		state->formats = format_create(NULL, NULL, FORMAT_NONE, 0);
+	format_merge(state->formats, ft);
+}
+
 /* Merge formats from item. */
 void
 cmdq_merge_formats(struct cmdq_item *item, struct format_tree *ft)
diff --git a/format.c b/format.c
index 2f7beb68..86263a25 100644
--- a/format.c
+++ b/format.c
@@ -929,6 +929,9 @@ format_cb_pane_fg(struct format_tree *ft)
 	struct window_pane	*wp = ft->wp;
 	struct grid_cell	 gc;
 
+	if (wp == NULL)
+		return (NULL);
+
 	tty_default_colours(&gc, wp);
 	return (xstrdup(colour_tostring(gc.fg)));
 }
@@ -940,6 +943,9 @@ format_cb_pane_bg(struct format_tree *ft)
 	struct window_pane	*wp = ft->wp;
 	struct grid_cell	 gc;
 
+	if (wp == NULL)
+		return (NULL);
+
 	tty_default_colours(&gc, wp);
 	return (xstrdup(colour_tostring(gc.bg)));
 }
@@ -3079,6 +3085,22 @@ format_free(struct format_tree *ft)
 	free(ft);
 }
 
+/* Log each format. */
+static void
+format_log_debug_cb(const char *key, const char *value, void *arg)
+{
+	const char	*prefix = arg;
+
+	log_debug("%s: %s=%s", prefix, key, value);
+}
+
+/* Log a format tree. */
+void
+format_log_debug(struct format_tree *ft, const char *prefix)
+{
+	format_each(ft, format_log_debug_cb, (void *)prefix);
+}
+
 /* Walk each format. */
 void
 format_each(struct format_tree *ft, void (*cb)(const char *, const char *,
diff --git a/notify.c b/notify.c
index 4b9b1eaa..9c55d0b8 100644
--- a/notify.c
+++ b/notify.c
@@ -25,31 +25,15 @@
 
 struct notify_entry {
 	const char		*name;
+	struct cmd_find_state	 fs;
+	struct format_tree	*formats;
 
 	struct client		*client;
 	struct session		*session;
 	struct window		*window;
 	int			 pane;
-
-	struct cmd_find_state	 fs;
 };
 
-static void
-notify_hook_formats(struct cmdq_state *state, struct session *s,
-    struct window *w, int pane)
-{
-	if (s != NULL) {
-		cmdq_add_format(state, "hook_session", "$%u", s->id);
-		cmdq_add_format(state, "hook_session_name", "%s", s->name);
-	}
-	if (w != NULL) {
-		cmdq_add_format(state, "hook_window", "@%u", w->id);
-		cmdq_add_format(state, "hook_window_name", "%s", w->name);
-	}
-	if (pane != -1)
-		cmdq_add_format(state, "hook_pane", "%%%d", pane);
-}
-
 static void
 notify_insert_hook(struct cmdq_item *item, struct notify_entry *ne)
 {
@@ -57,8 +41,6 @@ notify_insert_hook(struct cmdq_item *item, struct notify_entry *ne)
 	struct options			*oo;
 	struct cmdq_item		*new_item;
 	struct cmdq_state		*new_state;
-	struct session			*s = ne->session;
-	struct window			*w = ne->window;
 	struct options_entry		*o;
 	struct options_array_item	*a;
 	struct cmd_list			*cmdlist;
@@ -88,8 +70,7 @@ notify_insert_hook(struct cmdq_item *item, struct notify_entry *ne)
 		return;
 
 	new_state = cmdq_new_state(&fs, NULL, CMDQ_STATE_NOHOOKS);
-	cmdq_add_format(new_state, "hook", "%s", ne->name);
-	notify_hook_formats(new_state, s, w, ne->pane);
+	cmdq_add_formats(new_state, ne->formats);
 
 	a = options_array_first(o);
 	while (a != NULL) {
@@ -148,6 +129,7 @@ notify_callback(struct cmdq_item *item, void *data)
 	if (ne->fs.s != NULL)
 		session_remove_ref(ne->fs.s, __func__);
 
+	format_free(ne->formats);
 	free((void *)ne->name);
 	free(ne);
 
@@ -171,11 +153,23 @@ notify_add(const char *name, struct cmd_find_state *fs, struct client *c,
 	ne->client = c;
 	ne->session = s;
 	ne->window = w;
+	ne->pane = (wp != NULL ? wp->id : -1);
 
+	ne->formats = format_create(NULL, NULL, 0, FORMAT_NOJOBS);
+	format_add(ne->formats, "hook", "%s", name);
+	if (c != NULL)
+		format_add(ne->formats, "hook_client", "%s", c->name);
+	if (s != NULL) {
+		format_add(ne->formats, "hook_session", "$%u", s->id);
+		format_add(ne->formats, "hook_session_name", "%s", s->name);
+	}
+	if (w != NULL) {
+		format_add(ne->formats, "hook_window", "@%u", w->id);
+		format_add(ne->formats, "hook_window_name", "%s", w->name);
+	}
 	if (wp != NULL)
-		ne->pane = wp->id;
-	else
-		ne->pane = -1;
+		format_add(ne->formats, "hook_pane", "%%%d", wp->id);
+	format_log_debug(ne->formats, __func__);
 
 	if (c != NULL)
 		c->references++;
@@ -205,9 +199,14 @@ notify_hook(struct cmdq_item *item, const char *name)
 	ne.client = cmdq_get_client(item);
 	ne.session = target->s;
 	ne.window = target->w;
-	ne.pane = target->wp->id;
+	ne.pane = (target->wp != NULL ? target->wp->id : -1);
+
+	ne.formats = format_create(NULL, NULL, 0, FORMAT_NOJOBS);
+	format_add(ne.formats, "hook", "%s", name);
+	format_log_debug(ne.formats, __func__);
 
 	notify_insert_hook(item, &ne);
+	format_free(ne.formats);
 }
 
 void
diff --git a/tmux.1 b/tmux.1
index 1cda8e51..743584f8 100644
--- a/tmux.1
+++ b/tmux.1
@@ -4925,6 +4925,7 @@ The following variables are available, where appropriate:
 .It Li "history_limit" Ta "" Ta "Maximum window history lines"
 .It Li "history_size" Ta "" Ta "Size of history in lines"
 .It Li "hook" Ta "" Ta "Name of running hook, if any"
+.It Li "hook_client" Ta "" Ta "Name of client where hook was run, if any"
 .It Li "hook_pane" Ta "" Ta "ID of pane where hook was run, if any"
 .It Li "hook_session" Ta "" Ta "ID of session where hook was run, if any"
 .It Li "hook_session_name" Ta "" Ta "Name of session where hook was run, if any"
diff --git a/tmux.h b/tmux.h
index f35b2344..930bfa8b 100644
--- a/tmux.h
+++ b/tmux.h
@@ -2024,6 +2024,7 @@ void printflike(3, 4) format_add(struct format_tree *, const char *,
 void		 format_add_tv(struct format_tree *, const char *,
 		     struct timeval *);
 void		 format_add_cb(struct format_tree *, const char *, format_cb);
+void		 format_log_debug(struct format_tree *, const char *);
 void		 format_each(struct format_tree *, void (*)(const char *,
 		     const char *, void *), void *);
 char		*format_expand_time(struct format_tree *, const char *);
@@ -2383,6 +2384,7 @@ struct cmdq_state *cmdq_copy_state(struct cmdq_state *);
 void		  cmdq_free_state(struct cmdq_state *);
 void printflike(3, 4) cmdq_add_format(struct cmdq_state *, const char *,
 		     const char *, ...);
+void		  cmdq_add_formats(struct cmdq_state *, struct format_tree *);
 void		  cmdq_merge_formats(struct cmdq_item *, struct format_tree *);
 struct cmdq_list *cmdq_new(void);
 void cmdq_free(struct cmdq_list *);