diff --git a/lib/helpers/preferences_helper.dart b/lib/helpers/preferences_helper.dart
index b322936..35b0cb4 100644
--- a/lib/helpers/preferences_helper.dart
+++ b/lib/helpers/preferences_helper.dart
@@ -9,6 +9,10 @@ import 'package:shared_preferences/shared_preferences.dart';
 ///
 /// @author Pierre HUBERT
 
+enum PreferencesKeyList { LOGIN_TOKENS }
+
+const _PreferenceKeysName = {PreferencesKeyList.LOGIN_TOKENS: "login_tokens"};
+
 class PreferencesHelper {
   static PreferencesHelper _instance;
 
@@ -31,14 +35,14 @@ class PreferencesHelper {
 
   /// Set new login tokens
   Future<void> setLoginTokens(LoginTokens tokens) async {
-    await _sharedPreferences.setString(
-        "login_tokens", tokens == null ? "null" : tokens.toString());
+    await setString(PreferencesKeyList.LOGIN_TOKENS,
+        tokens == null ? "null" : tokens.toString());
   }
 
   /// Get current [LoginTokens]. Returns null if none or in case of failure
   LoginTokens getLoginTokens() {
     try {
-      final string = _sharedPreferences.getString("login_tokens");
+      final string = getString(PreferencesKeyList.LOGIN_TOKENS);
       if (string == null || string == "null") return null;
       return LoginTokens.fromJSON(jsonDecode(string));
     } on Exception catch (e) {
@@ -46,4 +50,12 @@ class PreferencesHelper {
       return null;
     }
   }
+
+  Future<void> setString(PreferencesKeyList key, String value) async {
+    await _sharedPreferences.setString(_PreferenceKeysName[key], value);
+  }
+
+  String getString(PreferencesKeyList key) {
+    return _sharedPreferences.getString(_PreferenceKeysName[key]);
+  }
 }