diff --git a/.ci/containers/build-environment/Dockerfile b/.ci/containers/build-environment/Dockerfile
index 7866dc9608cb..0a23367f577b 100644
--- a/.ci/containers/build-environment/Dockerfile
+++ b/.ci/containers/build-environment/Dockerfile
@@ -39,8 +39,8 @@ RUN git config --global user.email "magic-modules@google.com"
 RUN go install golang.org/x/tools/cmd/goimports@d088b475e3360caabc032aaee1dc66351d4e729a
 RUN go install github.com/github/hub@v2.11.2+incompatible
 
-ADD "https://raw.githubusercontent.com/GoogleCloudPlatform/magic-modules/main/mmv1/Gemfile" Gemfile
-ADD "https://raw.githubusercontent.com/GoogleCloudPlatform/magic-modules/main/mmv1/Gemfile.lock" Gemfile.lock
+ADD "https://raw.githubusercontent.com/GoogleCloudPlatform/magic-modules/refs/heads/legacy-ruby/mmv1/Gemfile" Gemfile
+ADD "https://raw.githubusercontent.com/GoogleCloudPlatform/magic-modules/refs/heads/legacy-ruby/mmv1/Gemfile.lock" Gemfile.lock
 RUN bundle install
 RUN rm Gemfile Gemfile.lock