diff --git a/docs/setup-dev-environment.md b/docs/setup-dev-environment.md
index 0bece44f..2508a346 100644
--- a/docs/setup-dev-environment.md
+++ b/docs/setup-dev-environment.md
@@ -255,9 +255,17 @@ Re-run the remaining migrations in `../migrations` to create the rest of the dat
 
 Now we are ready to run the application. The `APP_COOKIE_SECRET` is arbitrary.
 
-First `cd ./colouring-london/app`, then:
+First enter the app directory.
 
-`PGPASSWORD=<pgpassword> PGDATABASE=<colouringlondondb> PGUSER=<username> PGHOST=localhost PGPORT=5432 APP_COOKIE_SECRET=123456 TILECACHE_PATH=/path/to/tilecache/directory npm start`
+`cd ./colouring-london/app`
+
+Then create a folder for the tilecache.
+
+`mkdir tilecache`
+
+Finally, run the application.
+
+`PGPASSWORD=<pgpassword> PGDATABASE=<colouringlondondb> PGUSER=<username> PGHOST=localhost PGPORT=5432 APP_COOKIE_SECRET=123456 TILECACHE_PATH=./colouring-london/app/tilecache npm start`
 
 If you a running Ubuntu in a virtual environment you will need to configure networking to
 forward ports from the guest to the host. For Virtual Box the following was configured under