diff --git a/datasette/cli.py b/datasette/cli.py
index 90a33e80..1a495fee 100644
--- a/datasette/cli.py
+++ b/datasette/cli.py
@@ -496,6 +496,7 @@ def uninstall(packages, yes):
     "--internal",
     type=click.Path(),
     help="Path to a persistent Datasette internal SQLite database",
+    envvar="DATASETTE_INTERNAL",
 )
 def serve(
     files,