diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index 3100bf830333..5f4f43c23526 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -244,6 +244,10 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	/* Copy the LDT, if necessary. */
 	mdp1 = &td1->td_proc->p_md;
 	mdp2 = &p2->p_md;
+	if (mdp1->md_ldt == NULL) {
+		mdp2->md_ldt = NULL;
+		return;
+	}
 	mtx_lock(&dt_lock);
 	if (mdp1->md_ldt != NULL) {
 		if (flags & RFMEM) {