diff --git a/kernel/pid.c b/kernel/pid.c
index 8bce3aebc949..6a1d23a11026 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -657,7 +657,7 @@ void __init pid_idr_init(void)
 	idr_init(&init_pid_ns.idr);
 
 	init_pid_ns.pid_cachep = kmem_cache_create("pid",
-			struct_size((struct pid *)NULL, numbers, 1),
+			struct_size_t(struct pid, numbers, 1),
 			__alignof__(struct pid),
 			SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT,
 			NULL);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 70a929784a5d..0bf44afe04dd 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -48,7 +48,7 @@ static struct kmem_cache *create_pid_cachep(unsigned int level)
 		return kc;
 
 	snprintf(name, sizeof(name), "pid_%u", level + 1);
-	len = struct_size((struct pid *)NULL, numbers, level + 1);
+	len = struct_size_t(struct pid, numbers, level + 1);
 	mutex_lock(&pid_caches_mutex);
 	/* Name collision forces to do allocation under mutex. */
 	if (!*pkc)