diff --git a/Guide/testing.markdown b/Guide/testing.markdown
index 3e3358c38..6ddf81c0c 100644
--- a/Guide/testing.markdown
+++ b/Guide/testing.markdown
@@ -223,9 +223,12 @@ jobs:
         direnvVersion: 2.32.3
 
     - run: |
+          # Build generated files.
+          nix-shell --run "make build/Generated/Types.hs"
+
           # Start the project in the background.
           nix-shell --run "devenv up &"
 
           # Execute the tests.
           nix-shell --run "runghc $(make print-ghc-extensions) -i. -ibuild -iConfig Test/Main.hs"
-```
\ No newline at end of file
+```