diff --git a/.forgejo/workflows/build.yaml b/.forgejo/workflows/build.yaml
index c72ec45b..af39b76b 100644
--- a/.forgejo/workflows/build.yaml
+++ b/.forgejo/workflows/build.yaml
@@ -92,6 +92,7 @@ jobs:
               -cf - . | \
           docker run --rm -i \
             -e MIX_ENV=test \
+            -e MAKEFLAGS="-j1" \
             --network host \
             -w /app \
             docker.io/hexpm/elixir:1.20.1-erlang-29.0.2-debian-trixie-20260518-slim \