diff --git a/images/lib.sh b/images/lib.sh
index 1705e92..6663d0a 100644
--- a/images/lib.sh
+++ b/images/lib.sh
@@ -38,7 +38,7 @@ debootstrap() {
 
 upgrade_debs() {
     do_in_target apt-get update
-    do_in_target apt-get upgrade
+    do_in_target apt-get -y upgrade
 }
 
 secondstage() {