diff --git a/src/sna/sna_io.c b/src/sna/sna_io.c
index 6eede4df..3ce3dede 100644
--- a/src/sna/sna_io.c
+++ b/src/sna/sna_io.c
@@ -547,6 +547,7 @@ fallback:
 			int nbox_this_time, rem;
 
 			nbox_this_time = tmp_nbox;
+			rem = kgem_batch_space(kgem);
 			if (8*nbox_this_time > rem)
 				nbox_this_time = rem / 8;
 			if (2*nbox_this_time > KGEM_RELOC_SIZE(kgem) - kgem->nreloc)