diff --git a/datasette/cli.py b/datasette/cli.py
index 4363a28e..7887e642 100644
--- a/datasette/cli.py
+++ b/datasette/cli.py
@@ -497,6 +497,7 @@ def uninstall(packages, yes):
     "--internal",
     type=click.Path(),
     help="Path to a persistent Datasette internal SQLite database",
+    envvar="DATASETTE_INTERNAL",
 )
 def serve(
     files,
diff --git a/docs/cli-reference.rst b/docs/cli-reference.rst
index 2302f742..db903e8e 100644
--- a/docs/cli-reference.rst
+++ b/docs/cli-reference.rst
@@ -76,6 +76,8 @@ Or since this is the default command you can run this instead::
 
 Once started you can access it at ``http://localhost:8001``
 
+Use ``--internal PATH`` or the ``DATASETTE_INTERNAL`` environment variable to persist :ref:`Datasette's internal database <internals_internal>` to a SQLite file.
+
 .. [[[cog
     help(["serve", "--help"])
 .. ]]]
diff --git a/docs/internals.rst b/docs/internals.rst
index c05c7e27..8607e6b8 100644
--- a/docs/internals.rst
+++ b/docs/internals.rst
@@ -2473,7 +2473,20 @@ No token, cookie, or hidden form field is needed. Any ``<form method="POST">`` i
 Datasette's internal database
 =============================
 
-Datasette maintains an "internal" SQLite database used for configuration, caching, and storage. Plugins can store configuration, settings, and other data inside this database. By default, Datasette will use a temporary in-memory SQLite database as the internal database, which is created at startup and destroyed at shutdown. Users of Datasette can optionally pass in a ``--internal`` flag to specify the path to a SQLite database to use as the internal database, which will persist internal data across Datasette instances.
+Datasette maintains an "internal" SQLite database used for configuration, caching, and storage. Plugins can store configuration, settings, and other data inside this database. By default, Datasette will use a temporary in-memory SQLite database as the internal database, which is created at startup and destroyed at shutdown.
+
+To persist internal data across Datasette instances, use the ``--internal`` option to specify the path to a SQLite database:
+
+.. code-block:: bash
+
+    datasette mydatabase.db --internal internal.db
+
+You can also set the ``DATASETTE_INTERNAL`` environment variable to specify this path without passing ``--internal`` each time:
+
+.. code-block:: bash
+
+    export DATASETTE_INTERNAL=/path/to/internal.db
+    datasette mydatabase.db
 
 Datasette maintains tables called ``catalog_databases``, ``catalog_tables``, ``catalog_views``, ``catalog_columns``, ``catalog_indexes``, ``catalog_foreign_keys`` with details of the attached databases and their schemas. These tables should not be considered a stable API - they may change between Datasette releases.