diff --git a/gen-screenshot.ts b/gen-screenshot.ts
index 1cc20d3..9b30317 100755
--- a/gen-screenshot.ts
+++ b/gen-screenshot.ts
@@ -1,4 +1,4 @@
-#! /usr/bin/env -S deno run --allow-env --allow-net --allow-read --allow-run --allow-write
+#! /usr/bin/env -S deno run --allow-env --allow-net --allow-read --allow-run --allow-write --check
 // Generate the screenshot and its thumbnail for a project.
 // To install the dependencies on Debian/Ubuntu:
 // $ sudo apt install imagemagick optipng