diff --git a/debian/koha-common.maintscript b/debian/koha-common.maintscript
new file mode 100644
index 0000000000..8489567029
--- /dev/null
+++ b/debian/koha-common.maintscript
@@ -0,0 +1 @@
+rm_conffile /etc/init.d/koha-common 25.11~
diff --git a/debian/koha-systemd.postinst b/debian/koha-systemd.postinst
index 117d90c4c8..74f0eb8c22 100644
--- a/debian/koha-systemd.postinst
+++ b/debian/koha-systemd.postinst
@@ -6,26 +6,23 @@ case "$1" in
         # Reload systemd daemon
         systemctl daemon-reload || true
 
-        # Stop and disable the legacy SysV koha-common.service if present.
-        # This service is auto-generated by systemd-sysv-generator from
-        # /etc/init.d/koha-common and would run in parallel with the native
-        # systemd units, causing double-starts.
-        if systemctl is-active --quiet koha-common.service 2>/dev/null; then
-            systemctl stop koha-common.service || true
-        fi
-        if systemctl is-enabled --quiet koha-common.service 2>/dev/null; then
-            systemctl disable koha-common.service || true
-        fi
-        # Remove the orphaned SysV init script if it was left behind by
-        # the old koha-common package (pre-split) and koha-sysv is not installed.
-        if [ -f /etc/init.d/koha-common ] && ! dpkg -s koha-sysv >/dev/null 2>&1; then
-            rm -f /etc/init.d/koha-common
-            systemctl daemon-reload || true
-        fi
-
         # On first install (no previous version), enable units for all existing instances
         # This handles migration from SysV init to systemd
         if [ -z "$2" ]; then
+            # Stop and disable the legacy SysV koha-common.service if present.
+            # This service is auto-generated by systemd-sysv-generator from
+            # /etc/init.d/koha-common and would run in parallel with the native
+            # systemd units, causing double-starts. Only do this on first
+            # install: after migration, koha-common.service is our own compat
+            # unit, and stopping it here would stop every instance on each
+            # upgrade of this package.
+            if systemctl is-active --quiet koha-common.service 2>/dev/null; then
+                systemctl stop koha-common.service || true
+            fi
+            if systemctl is-enabled --quiet koha-common.service 2>/dev/null; then
+                systemctl disable koha-common.service || true
+            fi
+
             for instance in $(koha-list --enabled 2>/dev/null); do
                 # Core services: always enable
                 systemctl enable koha-zebra@${instance}.service 2>/dev/null || true