diff --git a/src/pacroller/config.json.example b/src/pacroller/config.json.example
index 997e270..beb1db9 100644
--- a/src/pacroller/config.json.example
+++ b/src/pacroller/config.json.example
@@ -17,7 +17,14 @@
         "/etc/pacman.d/mirrorlist"
     ],
     "need_restart": false,
-    "need_restart_cmd": ["needrestart", "-r", "a", "-m", "a", "-l"],
+    "need_restart_cmd": [
+        "needrestart",
+        "-r",
+        "a",
+        "-m",
+        "a",
+        "-l"
+    ],
     "systemd-check": true,
     "clear_pkg_cache": false
 }
diff --git a/src/pacroller/config.py b/src/pacroller/config.py
index 91d7ded..13804c6 100644
--- a/src/pacroller/config.py
+++ b/src/pacroller/config.py
@@ -58,7 +58,7 @@ for i in IGNORED_PACNEW:
     assert isinstance(i, str)
 
 NEEDRESTART = bool(_config.get('need_restart', False))
-NEEDRESTART_CMD = _config.get('need_restart_cmd', False)
+NEEDRESTART_CMD = _config.get('need_restart_cmd', ["needrestart", "-r", "a", "-m", "a", "-l"])
 for i in NEEDRESTART_CMD:
     assert isinstance(i, str)
 
diff --git a/src/pacroller/update-merge-config.py b/src/pacroller/update-merge-config.py
new file mode 100644
index 0000000..2a36a2b
--- /dev/null
+++ b/src/pacroller/update-merge-config.py
@@ -0,0 +1,49 @@
+#!/usr/bin/python
+
+from pacroller.config import CONFIG_DIR, CONFIG_FILE
+import json
+
+def main() -> None:
+    oldcfg = CONFIG_DIR / CONFIG_FILE
+    newcfg = CONFIG_DIR / f"{CONFIG_FILE}.pacnew"
+    assert oldcfg.exists()
+    assert newcfg.exists()
+    old: dict = json.loads(oldcfg.read_text())
+    new: dict = json.loads(newcfg.read_text())
+    new_copy = new.copy()
+    for k, v in new.items():
+        if isinstance(v, (int, str, bool)):
+            if old.get(k, None) is None:
+                print(f"use default value {k} = {v} for new option {k}")
+            else:
+                if old[k] != v:
+                    print(f"use custom value {k} = {old[k]} while default value is {v}")
+                    new_copy[k] = old[k]
+        elif isinstance(v, list):
+            if k == "need_restart_cmd":
+                if old[k] != v:
+                    print(f"use custom value {k} = {old[k]} while default value is {v}")
+                    new_copy[k] = old[k]
+            else:
+                _new = list()
+                for _item in [*old[k], *v]:
+                    if _item not in _new:
+                        _new.append(_item)
+                if _new != old[k]:
+                    print(f"merged {old[k]} and {v} to {_new}")
+                    new_copy[k] = _new
+        elif isinstance(v, dict):
+            for _o in old.get(k, {}):
+                if v.get(_o) != old[k][_o]:
+                    print(f"use custom value {k}[{_o}] = {old[k][_o]} while default value is {v.get(_o)}")
+                    new_copy[k][_o] = old[k][_o]
+            for _o in v:
+                if _o not in old.get(k, {}):
+                    print(f"new value {k}[{_o}] = {v[_o]}")
+
+    oldcfg.rename(CONFIG_DIR / f"{CONFIG_FILE}.pacsave")
+    oldcfg.write_text(json.dumps(new_copy, indent=4))
+    print("wrote new config")
+
+if __name__ == '__main__':
+    main()