diff --git a/tests/buildkite/pipeline-win64.yml b/tests/buildkite/pipeline-win64.yml
index afb6aafba..d4d171b02 100644
--- a/tests/buildkite/pipeline-win64.yml
+++ b/tests/buildkite/pipeline-win64.yml
@@ -1,5 +1,6 @@
 steps:
   - block: ":rocket: Run this test job"
+    if: build.pull_request.repository.fork == true
   #### -------- BUILD --------
   - label: ":windows: Build XGBoost for Windows with CUDA"
     command: "tests/buildkite/build-win64-gpu.ps1"
diff --git a/tests/buildkite/pipeline.yml b/tests/buildkite/pipeline.yml
index 7180e0f50..86763e75c 100644
--- a/tests/buildkite/pipeline.yml
+++ b/tests/buildkite/pipeline.yml
@@ -3,6 +3,7 @@ env:
   DOCKER_CACHE_ECR_REGION: "us-west-2"
 steps:
   - block: ":rocket: Run this test job"
+    if: build.pull_request.repository.fork == true
   #### -------- BUILD --------
   - label: ":console: Run clang-tidy"
     command: "tests/buildkite/run-clang-tidy.sh"