diff --git a/screen-write.c b/screen-write.c
index 8e9ec582..e351a5e5 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -769,6 +769,9 @@ screen_write_mode_set(struct screen_write_ctx *ctx, int mode)
 	struct screen	*s = ctx->s;
 
 	s->mode |= mode;
+
+	if (log_get_level() != 0)
+		log_debug("%s: %s", __func__, screen_mode_to_string(mode));
 }
 
 /* Clear a mode. */
@@ -778,6 +781,9 @@ screen_write_mode_clear(struct screen_write_ctx *ctx, int mode)
 	struct screen	*s = ctx->s;
 
 	s->mode &= ~mode;
+
+	if (log_get_level() != 0)
+		log_debug("%s: %s", __func__, screen_mode_to_string(mode));
 }
 
 /* Cursor up by ny. */
diff --git a/screen.c b/screen.c
index 464be1cb..30b448e8 100644
--- a/screen.c
+++ b/screen.c
@@ -155,8 +155,8 @@ screen_reset_tabs(struct screen *s)
 void
 screen_set_cursor_style(struct screen *s, u_int style)
 {
-	switch (style)
-	{
+	log_debug("%s: new %u, was %u", __func__, style, s->cstyle);
+	switch (style) {
 	case 0:
 		s->cstyle = SCREEN_CURSOR_DEFAULT;
 		break;
@@ -652,3 +652,51 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 	if (s->cy > screen_size_y(s) - 1)
 		s->cy = screen_size_y(s) - 1;
 }
+
+/* Get mode as a string. */
+const char *
+screen_mode_to_string(int mode)
+{
+	static char	tmp[1024];
+
+	if (mode == 0)
+		return "NONE";
+	if (mode == ALL_MODES)
+		return "ALL";
+
+	*tmp = '\0';
+	if (mode & MODE_CURSOR)
+		strlcat(tmp, "CURSOR,", sizeof tmp);
+	if (mode & MODE_INSERT)
+		strlcat(tmp, "INSERT,", sizeof tmp);
+	if (mode & MODE_KCURSOR)
+		strlcat(tmp, "KCURSOR,", sizeof tmp);
+	if (mode & MODE_KKEYPAD)
+		strlcat(tmp, "KKEYPAD,", sizeof tmp);
+	if (mode & MODE_WRAP)
+		strlcat(tmp, "WRAP,", sizeof tmp);
+	if (mode & MODE_MOUSE_STANDARD)
+		strlcat(tmp, "STANDARD,", sizeof tmp);
+	if (mode & MODE_MOUSE_BUTTON)
+		strlcat(tmp, "BUTTON,", sizeof tmp);
+	if (mode & MODE_BLINKING)
+		strlcat(tmp, "BLINKING,", sizeof tmp);
+	if (mode & MODE_MOUSE_UTF8)
+		strlcat(tmp, "UTF8,", sizeof tmp);
+	if (mode & MODE_MOUSE_SGR)
+		strlcat(tmp, "SGR,", sizeof tmp);
+	if (mode & MODE_BRACKETPASTE)
+		strlcat(tmp, "BRACKETPASTE,", sizeof tmp);
+	if (mode & MODE_FOCUSON)
+		strlcat(tmp, "FOCUSON,", sizeof tmp);
+	if (mode & MODE_MOUSE_ALL)
+		strlcat(tmp, "ALL,", sizeof tmp);
+	if (mode & MODE_ORIGIN)
+		strlcat(tmp, "ORIGIN,", sizeof tmp);
+	if (mode & MODE_CRLF)
+		strlcat(tmp, "CRLF,", sizeof tmp);
+	if (mode & MODE_KEXTENDED)
+		strlcat(tmp, "KEXTENDED,", sizeof tmp);
+	tmp[strlen (tmp) - 1] = '\0';
+	return (tmp);
+}
diff --git a/server-client.c b/server-client.c
index e74d893d..e3a690bd 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1691,7 +1691,10 @@ server_client_reset_state(struct client *c)
 		s = wp->screen;
 	if (s != NULL)
 		mode = s->mode;
-	log_debug("%s: client %s mode %x", __func__, c->name, mode);
+	if (log_get_level() != 0) {
+		log_debug("%s: client %s mode %s", __func__, c->name,
+		    screen_mode_to_string(mode));
+	}
 
 	/* Reset region and margin. */
 	tty_region_off(tty);
diff --git a/tmux.h b/tmux.h
index e54eb2d0..3fa7dfb3 100644
--- a/tmux.h
+++ b/tmux.h
@@ -2750,6 +2750,7 @@ void	 screen_select_cell(struct screen *, struct grid_cell *,
 	     const struct grid_cell *);
 void	 screen_alternate_on(struct screen *, struct grid_cell *, int);
 void	 screen_alternate_off(struct screen *, struct grid_cell *, int);
+const char *screen_mode_to_string(int);
 
 /* window.c */
 extern struct windows windows;
diff --git a/tty.c b/tty.c
index 367f54d5..45868fc1 100644
--- a/tty.c
+++ b/tty.c
@@ -665,8 +665,12 @@ tty_update_mode(struct tty *tty, int mode, struct screen *s)
 		mode &= ~MODE_CURSOR;
 
 	changed = mode ^ tty->mode;
-	if (changed != 0)
-		log_debug("%s: update mode %x to %x", c->name, tty->mode, mode);
+	if (log_get_level() != 0 && changed != 0) {
+		log_debug("%s: current mode %s", c->name,
+		    screen_mode_to_string(tty->mode));
+		log_debug("%s: setting mode %s", c->name,
+		    screen_mode_to_string(mode));
+	}
 
 	if (s != NULL) {
 		if (strcmp(s->ccolour, tty->ccolour) != 0)