diff --git a/src/sna/kgem.c b/src/sna/kgem.c
index ecd3674d..1e1da04e 100644
--- a/src/sna/kgem.c
+++ b/src/sna/kgem.c
@@ -4641,6 +4641,8 @@ static bool aperture_check(struct kgem *kgem, unsigned num_pages)
 
 		/* Leave some space in case of alignment issues */
 		aperture.aper_available_size -= 4 * 1024 * 1024;
+		if (kgem->gen < 040)
+			aperture.aper_available_size -= kgem->aperture_fenced * PAGE_SIZE;
 
 		if (num_pages < aperture.aper_available_size / PAGE_SIZE)
 			return true;