diff --git a/lib/types.nix b/lib/types.nix
index 67f3c4f..f06e0eb 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -1,4 +1,4 @@
-{ lib, ... }:
+{ lib, config, ... }:
 let
   ##############################################################################
   # Types for storing settings.
@@ -13,7 +13,7 @@ let
       };
       immutable = lib.mkOption {
         type = bool;
-        default = false;
+        default = config.programs.plasma.immutableByDefault;
         description = ''
           Whether to make the key immutable. This corresponds to adding [$i] to
           the end of the key.
diff --git a/lib/writeconfig.nix b/lib/writeconfig.nix
index 8a2c64b..c960c05 100644
--- a/lib/writeconfig.nix
+++ b/lib/writeconfig.nix
@@ -23,9 +23,10 @@ let
           resetFilesList ++ [ "${config.xdg.dataHome}/plasma-manager/last_run_*" ]
         else
           resetFilesList);
+      immutableByDefault = (builtins.toString config.programs.plasma.immutableByDefault);
     in
     ''
-      ${writeConfigScript}/bin/write_config ${jsonFile} "${resetFilesStr}"
+      ${writeConfigScript}/bin/write_config ${jsonFile} "${resetFilesStr}" "${immutableByDefault}"
     '';
 in
 {
diff --git a/modules/apps/konsole.nix b/modules/apps/konsole.nix
index 05aaa8d..d59ee30 100644
--- a/modules/apps/konsole.nix
+++ b/modules/apps/konsole.nix
@@ -1,6 +1,6 @@
 { config, lib, pkgs, ... }:
 let
-  inherit (import ../../lib/types.nix { inherit lib; }) basicSettingsType;
+  inherit (import ../../lib/types.nix { inherit lib; inherit config; }) basicSettingsType;
 
   # used as shown in the example in the library docs:
   # https://ryantm.github.io/nixpkgs/functions/library/attrsets/#function-library-lib.attrsets.mapAttrs-prime
diff --git a/modules/files.nix b/modules/files.nix
index 6c1d98d..61c45cf 100644
--- a/modules/files.nix
+++ b/modules/files.nix
@@ -3,7 +3,7 @@
 
 let
   inherit (import ../lib/writeconfig.nix { inherit lib pkgs config; }) writeConfig;
-  inherit (import ../lib/types.nix { inherit lib; }) coercedSettingsType;
+  inherit (import ../lib/types.nix { inherit lib; inherit config; }) coercedSettingsType;
 
   # Helper function to prepend the appropriate path prefix (e.g. XDG_CONFIG_HOME) to file
   prependPath = prefix: attrset:
@@ -114,6 +114,7 @@ in
         Config-files which explicitly should not be deleted on each generation.
       '';
     };
+    immutableByDefault = lib.mkEnableOption "Make keys written by plasma-manager immutable by default.";
   };
 
   imports = [
diff --git a/script/write_config.py b/script/write_config.py
index b2b93bf..c914a8c 100644
--- a/script/write_config.py
+++ b/script/write_config.py
@@ -138,7 +138,9 @@ class ConfigValue:
 
 
 class KConfManager:
-    def __init__(self, filepath: str, json_dict: Dict, reset: bool):
+    def __init__(
+        self, filepath: str, json_dict: Dict, reset: bool, immutable_by_default: bool
+    ):
         """
         filepath (str): The full path to the config-file to manage
         json_dict (Dict): The nix-configuration presented in a dictionary (converted from json)
@@ -148,6 +150,7 @@ class KConfManager:
         self.json_dict = json_dict
         self.filepath = filepath
         self.reset = reset
+        self.immutable_by_default = immutable_by_default
         self._json_value_checks()
         # The nix expressions will have / to separate groups, and \/ to escape a /.
         # This parses the groups into tuples of unescaped group names.
@@ -162,35 +165,32 @@ class KConfManager:
     def _json_value_checks(self):
         for group, entry in self.json_dict.items():
             for key, value in entry.items():
-                if value["immutable"] and value["value"] is None:
-                    # We don't allow immutability for keys with no value given (it doesn't make sense).
+                non_default_immutability = (
+                    value["immutable"] != self.immutable_by_default
+                )
+                if (
+                    value["value"] is None
+                    and not value["persistent"]
+                    and (non_default_immutability or value["shellExpand"])
+                ):
                     raise Exception(
-                        f'Plasma-manager: Immutability enabled for key "{key}" in group "{group}" in configfile "{self.filepath}"'
-                        " with no value set. Keys without values cannot be declared immutable"
-                    )
-                if value["shellExpand"] and value["value"] is None:
-                    # We don't allow immutability for keys with no value given (it doesn't make sense).
-                    raise Exception(
-                        f'Plasma-manager: Shell-expansion enabled for key "{key}" in group "{group}" in configfile "{self.filepath}"'
-                        " with no value set. Keys without values cannot have shell-expansion enabled"
+                        f'Plasma-manager: No value or persistency set for key "{key}" in group "{group}" in configfile "{self.filepath}"'
+                        ", but one of immutability/persistency takes a non-default value. This is not supported"
                     )
                 elif value["persistent"]:
                     base_msg = f'Plasma-manager: Persistency enabled for key "{key}" in group "{group}" in configfile "{self.filepath}"'
-                    # We don't allow persistency when the value is set,
-                    # immutability is enabled, or when shell-expansion is
-                    # enabled.
                     if value["value"] is not None:
                         raise Exception(
                             f"{base_msg} with non-null value \"{value['value']}\". "
                             "A value cannot be given when persistency is enabled"
                         )
-                    elif value["immutable"]:
+                    elif non_default_immutability:
                         raise Exception(
-                            f"{base_msg} with immutability enabled. Persistency and immutability cannot both be enabled"
+                            f"{base_msg} with non-default immutability. Persistency with non-default immutability is not supported"
                         )
                     elif value["shellExpand"]:
                         raise Exception(
-                            f"{base_msg} with shell-expansion enabled. Persistency and shell-expansion cannot both be enabled"
+                            f"{base_msg} with shell-expansion enabled. Persistency with shell-expansion enabled is not supported"
                         )
 
     def key_is_persistent(self, group, key) -> bool:
@@ -308,15 +308,17 @@ def remove_config_files(d: Dict, reset_files: Set):
                 os.remove(file_to_del)
 
 
-def write_configs(d: Dict, reset_files: Set):
+def write_configs(d: Dict, reset_files: Set, immutable_by_default: bool):
     for filepath, c in d.items():
-        config = KConfManager(filepath, c, filepath in reset_files)
+        config = KConfManager(
+            filepath, c, filepath in reset_files, immutable_by_default
+        )
         config.run()
         config.save()
 
 
 def main():
-    if len(sys.argv) != 3:
+    if len(sys.argv) != 4:
         raise ValueError(
             f"Must receive exactly two arguments, got: {len(sys.argv) - 1}"
         )
@@ -325,10 +327,11 @@ def main():
     with open(json_path, "r") as f:
         json_str = f.read()
 
-    reset_files = set(sys.argv[2].split(" ")) if len(sys.argv) >= 2 else {}
+    reset_files = set(sys.argv[2].split(" ")) if sys.argv[2] != "" else set()
+    immutable_by_default = bool(sys.argv[3])
     d = json.loads(json_str)
     remove_config_files(d, reset_files)
-    write_configs(d, reset_files)
+    write_configs(d, reset_files, immutable_by_default)
 
 
 if __name__ == "__main__":