diff --git a/sys/i386/i386/sys_machdep.c b/sys/i386/i386/sys_machdep.c
index 68bb0a45ef3..f6aca9cd749 100644
--- a/sys/i386/i386/sys_machdep.c
+++ b/sys/i386/i386/sys_machdep.c
@@ -444,8 +444,9 @@ user_ldt_alloc(struct mdproc *mdp, int len)
         new_ldt->ldt_base = (caddr_t)kmem_alloc(kernel_map, 
                 round_page(len * sizeof(union descriptor))); 
         if (new_ldt->ldt_base == NULL) { 
-                FREE(new_ldt, M_SUBPROC); 
-                return NULL; 
+                FREE(new_ldt, M_SUBPROC);
+		mtx_lock_spin(&dt_lock);
+                return (NULL);
         } 
         new_ldt->ldt_refcnt = 1; 
         new_ldt->ldt_active = 0; 
@@ -460,7 +461,7 @@ user_ldt_alloc(struct mdproc *mdp, int len)
         } 
         pmap_map_readonly(kernel_pmap, (vm_offset_t)new_ldt->ldt_base, 
                           new_ldt->ldt_len*sizeof(union descriptor)); 
-        return new_ldt; 
+        return (new_ldt);
 } 
 #else
 /*
@@ -481,7 +482,8 @@ user_ldt_alloc(struct mdproc *mdp, int len)
 		len * sizeof(union descriptor));
 	if (new_ldt->ldt_base == NULL) {
 		FREE(new_ldt, M_SUBPROC);
-		return NULL;
+		mtx_lock_spin(&dt_lock);
+		return (NULL);
 	}
 	new_ldt->ldt_refcnt = 1;
 	new_ldt->ldt_active = 0;
@@ -513,8 +515,10 @@ user_ldt_free(struct thread *td)
 	struct proc_ldt *pldt;
 
 	mtx_assert(&dt_lock, MA_OWNED);
-	if ((pldt = mdp->md_ldt) == NULL)
+	if ((pldt = mdp->md_ldt) == NULL) {
+		mtx_unlock_spin(&dt_lock);
 		return;
+	}
 
 	if (td == PCPU_GET(curthread)) {
 		lldt(_default_ldt);