diff --git a/rainfallwrangler/src/subcommands/recompress/meta.mjs b/rainfallwrangler/src/subcommands/recompress/meta.mjs
index 4a6aca8..ed06b5a 100644
--- a/rainfallwrangler/src/subcommands/recompress/meta.mjs
+++ b/rainfallwrangler/src/subcommands/recompress/meta.mjs
@@ -1,7 +1,7 @@
 "use strict";
 
 export default function(cli) {
-	cli.subcommand("recompress", "Recompress a source to a target directory with a given number of records per file.")
+	cli.subcommand("recompress", "Recompress a source .jsonl.gz to a target directory with a given number of records per file.")
 		.argument("source", "Path to the source directory.", null, "string")
 		.argument("target", "Path to the target directory.", null, "string")
 		.argument("count-file", "The number of records to store in each record file. See the documentation for the optimal value of this number (default: 4096).", 64*64, "integer");