diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index fe95e28ec..44649e818 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -369,6 +369,7 @@ Test your code and make sure it passes.
 2. run `npm install`
 3. run `npm test` to see whether your tests pass or fail.
 
+Note that in order to run the tests, Chrome needs to be installed on the system. Chromium can be used as an alternative, but requires setting the environment variable `CHROME_BIN` to the corresponding executable (e.g. `export CHROME_BIN="`which chromium`"`).
 
 ### Building / Installing