diff --git a/stack.sh b/stack.sh
index f6b5e9e..55c8a45 100755
--- a/stack.sh
+++ b/stack.sh
@@ -990,10 +990,10 @@
     clean_iptables
 
     # Destroy old instances
-    instances=`virsh list --all | grep $INSTANCE_NAME_PREFIX | sed "s/.*\($INSTANCE_NAME_PREFIX[0-9a-fA-F]*\).*/\1/g"`
+    instances=`sudo virsh list --all | grep $INSTANCE_NAME_PREFIX | sed "s/.*\($INSTANCE_NAME_PREFIX[0-9a-fA-F]*\).*/\1/g"`
     if [ ! "$instances" = "" ]; then
-        echo $instances | xargs -n1 virsh destroy || true
-        echo $instances | xargs -n1 virsh undefine || true
+        echo $instances | xargs -n1 sudo virsh destroy || true
+        echo $instances | xargs -n1 sudo virsh undefine || true
     fi
 
     # Logout and delete iscsi sessions