diff --git a/src/test/test-process-util.c b/src/test/test-process-util.c
index fd4d17408d..7f3f502c56 100644
--- a/src/test/test-process-util.c
+++ b/src/test/test-process-util.c
@@ -206,7 +206,7 @@ static void test_get_process_cmdline_harder(void) {
         assert_se(pid == 0);
         assert_se(unshare(CLONE_NEWNS) >= 0);
 
-        assert_se(mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) >= 0);
+        assert_se(mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) >= 0);
 
         fd = mkostemp(path, O_CLOEXEC);
         assert_se(fd >= 0);
diff --git a/src/test/test-udev.c b/src/test/test-udev.c
index bed51c1270..dd630b9718 100644
--- a/src/test/test-udev.c
+++ b/src/test/test-udev.c
@@ -38,7 +38,7 @@ static int fake_filesystems(void) {
         if (unshare(CLONE_NEWNS) < 0)
                 return log_error_errno(errno, "failed to call unshare(): %m");
 
-        if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0)
+        if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0)
                 return log_error_errno(errno, "failed to mount / as private: %m");
 
         for (i = 0; i < ELEMENTSOF(fakefss); i++) {