diff --git a/vm/vm_page.c b/vm/vm_page.c
--- a/vm/vm_page.c
+++ b/vm/vm_page.c
@@ -4106,7 +4106,8 @@
 	bits = vm_page_bits(base, size);
 	m->valid &= ~bits;
 	m->dirty &= ~bits;
-	atomic_add_int(&m->object->generation, 1);
+	if (m->object)
+		atomic_add_int(&m->object->generation, 1);
 }
 
 /*