diff --git a/buildiso.sh b/buildiso.sh
index b157c7f..d80dc91 100755
--- a/buildiso.sh
+++ b/buildiso.sh
@@ -13,8 +13,9 @@ fail() {
 }
 
 which debootstrap &>/dev/null || fail "This script requires debootstrap."
-which mksquashfs &>/dev/null || fail "This script requires squashfs."
+which mksquashfs &>/dev/null || fail "This script requires squashfs-tools."
 which xorriso &>/dev/null || fail "This script requires xorriso."
+test -f /usr/lib/ISOLINUX/isohdpfx.bin &>/dev/null || fail "This script requires isolinux."
 
 isofilename="pvc-installer_$(date +%Y-%m-%d).iso"
 srcliveisourl="https://cdimage.debian.org/mirror/cdimage/buster_di_rc1-live/amd64/iso-hybrid/debian-live-buster-DI-rc1-amd64-standard.iso"