diff --git a/archiso/build_archiso.sh b/archiso/build_archiso.sh
index 19123ae..cb879c8 100755
--- a/archiso/build_archiso.sh
+++ b/archiso/build_archiso.sh
@@ -1,3 +1,5 @@
+set -e
+
 build="archiso-profile-do-not-delete"
 out="built-isos"
 profile="releng"
@@ -13,6 +15,12 @@ cp installer/install-arch $build/$profile/airootfs/root/
 # e.g. a custom pacman.conf
 cp -r archiso/profile/. $build/$profile
 
+# add custom repository to pacman.conf
+cat >> $build/$profile/pacman.conf <<EOF
+[mkessler-arch]
+Server = https://mkessler-arch.maximilian-kessler.de
+EOF
+
 # install additional packages used by installer script
 cat >> $build/$profile/packages.x86_64 <<EOF
 pacman-contrib