diff --git a/mkosi/mkosi.postinst.chroot b/mkosi/mkosi.postinst.chroot
index eb6d917025..de67ddfdc8 100755
--- a/mkosi/mkosi.postinst.chroot
+++ b/mkosi/mkosi.postinst.chroot
@@ -27,8 +27,9 @@ mountpoint -q /etc/resolv.conf && umount /etc/resolv.conf
 rm -f /etc/resolv.conf
 
 for f in "$BUILDROOT"/usr/share/*.verity.sig; do
-    jq --join-output '.rootHash' "$f" >"${f%.verity.sig}.roothash"
-    jq --join-output '.signature' "$f" | base64 --decode >"${f%.verity.sig}.roothash.p7s"
+    # jq started refusing input with NUL bytes padding
+    strings "$f" | jq --join-output '.rootHash' >"${f%.verity.sig}.roothash"
+    strings "$f" | jq --join-output '.signature' | base64 --decode >"${f%.verity.sig}.roothash.p7s"
 done
 
 # We want /var/log/journal to be created on first boot so it can be created with the right chattr settings by