diff --git a/t/runtest b/t/runtest
index b4e0677..bf74491 100755
--- a/t/runtest
+++ b/t/runtest
@@ -38,7 +38,12 @@ echo "Downloading image"
 [ ! -e /tmp/libvirt.box ] && curl -L -s $IMAGE > /tmp/libvirt.box
 [ ! -e /tmp/box.img ] && tar -zxvf /tmp/libvirt.box box.img
 mv -f box.img /tmp/disk1.qcow2
-[ ! -e /tmp/disk2.qcow2 ] &&  qemu-img create -f qcow2 /tmp/disk2.qcow2 10M
+if [ -n "${DEBUG_BIG}" ]; then
+    echo "two big disks"
+    cp /tmp/disk1.qcow2 /tmp/disk2.qcow2
+else
+    [ ! -e /tmp/disk2.qcow2 ] &&  qemu-img create -f qcow2 /tmp/disk2.qcow2 10M
+fi
 [ ! -e /tmp/disk3.raw ] && qemu-img create -f raw /tmp/disk3.raw 10M
 
 echo "Starting qemu process"