diff --git a/dmenu_charinput.sh b/dmenu_charinput.sh
index 8329624..4569ba6 100755
--- a/dmenu_charinput.sh
+++ b/dmenu_charinput.sh
@@ -1,5 +1,8 @@
 #!/bin/sh
 
+# call this with a single 'ranges' parameter for unicodedata
+# e.g. dmenu_charinput.sh '13000..1342F 1F600..1F64F'
+
 set -eu
 
 unicodedata -ranges "$1" |