diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index f2952a65dcc2e6..23bb9a9e6a7d73 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -508,6 +508,9 @@ int cgroup_setup_and_join(const char *path) {
 /**
  * setup_classid_environment() - Setup the cgroupv1 net_cls environment
  *
+ * This function should only be called in a custom mount namespace, e.g.
+ * created by running setup_cgroup_environment.
+ *
  * After calling this function, cleanup_classid_environment should be called
  * once testing is complete.
  *
diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup1_hierarchy.c b/tools/testing/selftests/bpf/prog_tests/cgroup1_hierarchy.c
index 74d6d7546f40fa..25332e596750fa 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgroup1_hierarchy.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup1_hierarchy.c
@@ -87,9 +87,12 @@ void test_cgroup1_hierarchy(void)
 		goto destroy;
 
 	/* Setup cgroup1 hierarchy */
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto destroy;
 	err = setup_classid_environment();
 	if (!ASSERT_OK(err, "setup_classid_environment"))
-		goto destroy;
+		goto cleanup_cgroup;
 
 	err = join_classid();
 	if (!ASSERT_OK(err, "join_cgroup1"))
@@ -153,6 +156,8 @@ void test_cgroup1_hierarchy(void)
 
 cleanup:
 	cleanup_classid_environment();
+cleanup_cgroup:
+	cleanup_cgroup_environment();
 destroy:
 	test_cgroup1_hierarchy__destroy(skel);
 }