diff --git a/sys/fs/nfsclient/nfs_clbio.c b/sys/fs/nfsclient/nfs_clbio.c
index bae44edee046..0eb30f990d48 100644
--- a/sys/fs/nfsclient/nfs_clbio.c
+++ b/sys/fs/nfsclient/nfs_clbio.c
@@ -306,7 +306,8 @@ ncl_getpages(struct vop_getpages_args *ap)
 			 * Read operation filled an entire page
 			 */
 			m->valid = VM_PAGE_BITS_ALL;
-			vm_page_undirty(m);
+			KASSERT(m->dirty == 0,
+			    ("nfs_getpages: page %p is dirty", m));
 		} else if (size > toff) {
 			/*
 			 * Read operation filled a partial page.