diff --git a/format.c b/format.c
index 2275090e..0845df6d 100644
--- a/format.c
+++ b/format.c
@@ -410,6 +410,15 @@ format_winlink(struct format_tree *ft, struct session *s, struct winlink *wl)
 	format_add(ft, "window_active", "%d", wl == s->curw);
 	format_add(ft, "window_panes", "%u", window_count_panes(w));
 
+	format_add(ft, "window_bell_flag", "%u",
+	    !!(wl->flags & WINLINK_BELL));
+	format_add(ft, "window_content_flag", "%u",
+	    !!(wl->flags & WINLINK_CONTENT));
+	format_add(ft, "window_activity_flag", "%u",
+	    !!(wl->flags & WINLINK_ACTIVITY));
+	format_add(ft, "window_silence_flag", "%u",
+	    !!(wl->flags & WINLINK_SILENCE));
+
 	free(flags);
 	free(layout);
 }
diff --git a/tmux.1 b/tmux.1
index 11251790..340109b6 100644
--- a/tmux.1
+++ b/tmux.1
@@ -3096,6 +3096,9 @@ The following variables are available, where appropriate:
 .It Li "session_width" Ta "" Ta "Width of session"
 .It Li "session_windows" Ta "" Ta "Number of windows in session"
 .It Li "window_active" Ta "" Ta "1 if window active"
+.It Li "window_activity_flag" Ta "" Ta "1 if window has activity alert"
+.It Li "window_bell_flag" Ta "" Ta "1 if window has bell"
+.It Li "window_content_flag" Ta "" Ta "1 if window has content alert"
 .It Li "window_find_matches" Ta "" Ta "Matched data from the find-window"
 .It Li "window_flags" Ta "#F" Ta "Window flags"
 .It Li "window_height" Ta "" Ta "Height of window"
@@ -3104,6 +3107,7 @@ The following variables are available, where appropriate:
 .It Li "window_layout" Ta "" Ta "Window layout description"
 .It Li "window_name" Ta "#W" Ta "Name of window"
 .It Li "window_panes" Ta "" Ta "Number of panes in window"
+.It Li "window_silence_flag" Ta "" Ta "1 if window has silence alert"
 .It Li "window_width" Ta "" Ta "Width of window"
 .It Li "wrap_flag" Ta "" Ta "Pane wrap flag"
 .El