diff --git a/source/contribute/development.html.md b/source/contribute/development.html.md
index 014c29b..19b4bd2 100644
--- a/source/contribute/development.html.md
+++ b/source/contribute/development.html.md
@@ -133,6 +133,8 @@ then run `caddy`. You can now open your browser and load `https://plume01.localh
 
 ## Running tests
 
+To run tests, use `DATABASE_URL` for tests and run migration at first.
+
 To run tests of `plume-models` use `RUST_TEST_THREADS=1`, otherwise tests are run
 concurrently, which causes error because they all use the same database.