diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 331e4887c200..347ec7f70aaf 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1024,7 +1024,7 @@ vfs_donmount(struct thread *td, uint64_t fsflags, struct uio *fsoptions)
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
 		} else {
-			copyout(errmsg,
+			(void)copyout(errmsg,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
 		}