diff --git a/icon.go b/icon.go
index 6fcafd4..8a25874 100644
--- a/icon.go
+++ b/icon.go
@@ -287,6 +287,7 @@ const (
 
 	// status: checkbox
 	IconCheckboxChecked              Icon = "CheckboxChecked"
+	IconCheckboxUnchecked            Icon = "CheckboxUnchecked"
 	// status: appointments
 	IconAppointmentMissed            Icon = "AppointmentMissed"
 	IconAppointmentSoon              Icon = "AppointmentSoon"