diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
index 536c17b4d5..9c27972aff 100644
--- a/src/core/mount-setup.c
+++ b/src/core/mount-setup.c
@@ -248,6 +248,7 @@ int mount_setup_early(void) {
 
 int mount_cgroup_controllers(char ***join_controllers) {
         _cleanup_set_free_free_ Set *controllers = NULL;
+        bool has_argument = !!join_controllers;
         int r;
 
         if (!cg_is_legacy_wanted())
@@ -255,7 +256,7 @@ int mount_cgroup_controllers(char ***join_controllers) {
 
         /* Mount all available cgroup controllers that are built into the kernel. */
 
-        if (!join_controllers)
+        if (!has_argument)
                 /* The defaults:
                  * mount "cpu" + "cpuacct" together, and "net_cls" + "net_prio".
                  *
@@ -300,7 +301,8 @@ int mount_cgroup_controllers(char ***join_controllers) {
 
                                         t = set_remove(controllers, *i);
                                         if (!t) {
-                                                free(*i);
+                                                if (has_argument)
+                                                        free(*i);
                                                 continue;
                                         }
                                 }