diff --git a/check_licenses.sh b/check_licenses.sh
index 7cc4621..c02b162 100644
--- a/check_licenses.sh
+++ b/check_licenses.sh
@@ -1,3 +1,4 @@
 #!/bin/sh
+# Depends on: `rg` (ripgrep)
 
 ! rg --multiline --files-without-match --glob '*.rs' --pcre2  '(?<!\n)((//)|(#)) Copyright \(c\) \d+ [A-z, ]+\n((//)|(#)) SPDX-License-Identifier: .*\n'