diff --git a/ct/inventree.sh b/ct/inventree.sh
index 601727863..e5e8bf8a1 100644
--- a/ct/inventree.sh
+++ b/ct/inventree.sh
@@ -58,7 +58,9 @@ function update_script() {
 
   msg_info "Updating InvenTree"
   apt_update_safe
-  $STD apt install --only-upgrade inventree -y
+  # postinst loops forever unless its parent chain reaches PID 1 (not the case under pct exec)
+  $STD systemd-run --wait --pipe --quiet --collect --setenv=DEBIAN_FRONTEND=noninteractive \
+    apt-get install --only-upgrade -y inventree
   msg_ok "Updated InvenTree"
   msg_ok "Updated successfully!"
   exit
diff --git a/install/inventree-install.sh b/install/inventree-install.sh
index ff2fb25c7..bf2a07761 100644
--- a/install/inventree-install.sh
+++ b/install/inventree-install.sh
@@ -23,8 +23,10 @@ setup_deb822_repo \
 msg_ok "Set up InvenTree Repository"
 
 msg_info "Installing InvenTree (Patience)"
-export SETUP_NO_CALLS=true
-$STD apt install -y inventree
+# The package's postinst walks parent PIDs until it reaches PID 1; under pct exec the chain ends at 0
+# and since 1.6.0 that loops forever, so apt runs as a child of systemd
+$STD systemd-run --wait --pipe --quiet --collect --setenv=SETUP_NO_CALLS=true --setenv=DEBIAN_FRONTEND=noninteractive \
+  apt-get install -y inventree
 msg_ok "Installed InvenTree"
 
 msg_info "Configuring InvenTree"