diff --git a/composer.json b/composer.json
index f6b735e..504609a 100644
--- a/composer.json
+++ b/composer.json
@@ -2,12 +2,22 @@
     "name":              "jrosset/envreader",
     "description":       "Utility class for ENV file reading",
     "keywords":          [ ],
+    "type":              "library",
+
+    "config":            {
+        "sort-packages": true
+    },
+    "extra":             {
+        "branch-alias": {
+            "dev-master": "2.x-dev"
+        }
+    },
 
     "minimum-stability": "stable",
     "require":           {
         "php":                 "^7.4 || ^8.0",
-        "jrosset/singleton":   "^1.0",
-        "jrosset/collections": "^2.0"
+        "jrosset/singleton":   "^1.5",
+        "jrosset/collections": "^2.3 || ^3.0"
     },
     "autoload":          {
         "psr-4":                 {
diff --git a/src/EnvReader/GenericConfig.php b/src/EnvReader/GenericConfig.php
index 637f1ac..cc10bd5 100644
--- a/src/EnvReader/GenericConfig.php
+++ b/src/EnvReader/GenericConfig.php
@@ -8,6 +8,7 @@ use Exception;
 use jrosset\Collections\IArrayCast;
 use jrosset\Collections\InsensitiveCaseKeyCollection;
 use jrosset\Collections\InsensitiveCaseKeyImmutableCollection;
+use jrosset\Singleton\ISingleton;
 use jrosset\Singleton\TSingleton;
 use RangeException;
 use UnexpectedValueException;
@@ -17,7 +18,7 @@ use UnexpectedValueException;
  *
  * Overwrite {@see GenericConfig::initialProperties()} to set initial properties
  */
-abstract class GenericConfig {
+abstract class GenericConfig implements ISingleton {
     use TSingleton;
 
     /**