diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 58220f5..b7a02ef 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -3,8 +3,5 @@ platforms:
   ubuntu1604:
     build_targets:
     - "..."
-    # Tests cannot run concurrently as some of them open the same port.
-    test_flags:
-    - "--jobs=1"
     test_targets:
     - "..."
diff --git a/cartographer/cloud/BUILD.bazel b/cartographer/cloud/BUILD.bazel
index b491564..2cb0a6c 100644
--- a/cartographer/cloud/BUILD.bazel
+++ b/cartographer/cloud/BUILD.bazel
@@ -89,6 +89,8 @@ cc_binary(
     name = src.replace("/", "_").replace(".cc", ""),
     srcs = [src],
     data = ["//:configuration_files"],
+    # Tests cannot run concurrently as some of them open the same port.
+    tags = ["exclusive"],
     deps = [
         ":cartographer_grpc",
         "@com_google_googletest//:gtest_main",