diff --git a/format.c b/format.c
index 847ba08a..f799dfb5 100644
--- a/format.c
+++ b/format.c
@@ -1138,8 +1138,6 @@ format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
 	    !!(wp->base.mode & MODE_MOUSE_STANDARD));
 	format_add(ft, "mouse_button_flag", "%d",
 	    !!(wp->base.mode & MODE_MOUSE_BUTTON));
-	format_add(ft, "mouse_utf8_flag", "%d",
-	    !!(wp->base.mode & MODE_MOUSE_UTF8));
 
 	format_add_cb(ft, "pane_tabs", format_cb_pane_tabs);
 }
diff --git a/tmux.1 b/tmux.1
index 4420ac3a..a35c01f8 100644
--- a/tmux.1
+++ b/tmux.1
@@ -3394,7 +3394,6 @@ The following variables are available, where appropriate:
 .It Li "mouse_any_flag" Ta "" Ta "Pane mouse any flag"
 .It Li "mouse_button_flag" Ta "" Ta "Pane mouse button flag"
 .It Li "mouse_standard_flag" Ta "" Ta "Pane mouse standard flag"
-.It Li "mouse_utf8_flag" Ta "" Ta "Pane mouse UTF-8 flag"
 .It Li "pane_active" Ta "" Ta "1 if active pane"
 .It Li "pane_bottom" Ta "" Ta "Bottom of pane"
 .It Li "pane_current_command" Ta "" Ta "Current command if available"