diff --git a/cli.ts b/cli.ts
index aeead4c..0958a7d 100644
--- a/cli.ts
+++ b/cli.ts
@@ -1,8 +1,13 @@
 import { parseArgs } from "./deps.ts";
-import { options } from "./src/const.ts";
+import { options, USAGE } from "./src/const.ts";
 import { sweetid } from "./src/main.ts";
 
-const { count, size } = parseArgs(Deno.args, options);
+const { count, size, help } = parseArgs(Deno.args, options);
+
+if (help) {
+  console.log(USAGE);
+  Deno.exit();
+}
 
 for (let i = count; i > 0; i--) {
   console.log(sweetid(size));
diff --git a/src/const.ts b/src/const.ts
index 09c6878..4e22a8a 100644
--- a/src/const.ts
+++ b/src/const.ts
@@ -29,6 +29,8 @@ export const CharSets = {
 } as const;
 
 export const options: ParseOptions = {
+  boolean: ['help'],
+
   alias: {
     count: "c",
     size: "s",
@@ -38,4 +40,13 @@ export const options: ParseOptions = {
     count: 1,
     size: "xshort",
   },
+
+  unknown: () => {
+    console.log(USAGE);
+    Deno.exit(1);
+  }
 };
+
+export const USAGE = `
+See https://deno.land/x/sweetid for details.
+`;