diff --git a/packaging/freebsd/port/check-cargo-crates.sh b/packaging/freebsd/port/check-cargo-crates.sh
index 4fa5d8c..f361e21 100755
--- a/packaging/freebsd/port/check-cargo-crates.sh
+++ b/packaging/freebsd/port/check-cargo-crates.sh
@@ -1,4 +1,7 @@
 #!/bin/sh
+# Run as:  sh check-cargo-crates.sh   (or ./check-cargo-crates.sh)
+# A POSIX shell wrapper that calls python3 internally; run it with the shell.
+#
 # Verify the port Makefile's CARGO_CRATES matches the crates.io dependency
 # closure in Cargo.lock. Run after any dependency change (and in CI): if cargo
 # adds/removes/bumps a registry dep, CARGO_CRATES must be regenerated with