diff --git a/README.md b/README.md
index 2f232a2..10614e9 100644
--- a/README.md
+++ b/README.md
@@ -288,3 +288,13 @@ gulp dev --coverage # run with tests and code coverage
 
 - `src/ts/server/start.ts:35` - adding custom map to the world
 - `src/ts/server/map/customMap.ts` - commented introduction to customizing maps
+
+## Have git ignore changes to `sprites.ts`, eventhough it's already in the index
+
+Due to an issue with the build system, an old copy of `src/ts/generated/sprites.ts` is shipped with this repository. In order to prevent Git from seeing changes to this file from local builds and warning you about them when changing branches or pulling new changes, you can use the following command:
+
+```bash
+git update-index --assume-unchanged src/ts/generated/sprites.ts
+```
+
+Read more about it [here](https://stackoverflow.com/questions/1139762/ignore-files-that-have-already-been-committed-to-a-git-repository).