diff --git a/packages/backend/src/CoreModule.js b/packages/backend/src/CoreModule.js
index 489938ede..0a28490ad 100644
--- a/packages/backend/src/CoreModule.js
+++ b/packages/backend/src/CoreModule.js
@@ -17,6 +17,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 const { AdvancedBase } = require("@heyputer/puter-js-common");
+const Library = require("./definitions/Library");
 const { NotificationES } = require("./om/entitystorage/NotificationES");
 const { ProtectedAppES } = require("./om/entitystorage/ProtectedAppES");
 const { Context } = require('./util/context');
@@ -49,16 +50,19 @@ const install = async ({ services, app, useapi }) => {
     useapi.withuse(() => {
         def('Service', require('./services/BaseService'));
         def('Module', AdvancedBase);
+        def('Library', Library);
 
         def('puter.middlewares.auth', require('./middleware/auth2'));
     });
     
     // === LIBRARIES ===
-    const ArrayUtil = require('./libraries/ArrayUtil');
-    services.registerService('util-array', ArrayUtil);
+    useapi.withuse(() => {
+        const ArrayUtil = require('./libraries/ArrayUtil');
+        services.registerService('util-array', ArrayUtil);
     
-    const LibTypeTagged = require('./libraries/LibTypeTagged');
-    services.registerService('lib-type-tagged', LibTypeTagged);
+        const LibTypeTagged = require('./libraries/LibTypeTagged');
+        services.registerService('lib-type-tagged', LibTypeTagged);
+    });
     
     // === SERVICES ===
 
diff --git a/packages/backend/src/libraries/ArrayUtil.js b/packages/backend/src/libraries/ArrayUtil.js
index 20da4c73c..950e6093f 100644
--- a/packages/backend/src/libraries/ArrayUtil.js
+++ b/packages/backend/src/libraries/ArrayUtil.js
@@ -1,6 +1,4 @@
-const Library = require("../definitions/Library");
-
-class ArrayUtil extends Library {
+class ArrayUtil extends use.Library {
     /**
      * 
      * @param {*} marked_map 
diff --git a/packages/backend/src/libraries/LibTypeTagged.js b/packages/backend/src/libraries/LibTypeTagged.js
index f1da0006c..fbe80c72f 100644
--- a/packages/backend/src/libraries/LibTypeTagged.js
+++ b/packages/backend/src/libraries/LibTypeTagged.js
@@ -1,7 +1,6 @@
-const Library = require("../definitions/Library");
 const { whatis } = require("../util/langutil");
 
-class LibTypeTagged extends Library {
+class LibTypeTagged extends use.Library {
     process (o) {
         const could_be = whatis(o) === 'object' || Array.isArray(o);
         if ( ! could_be ) return {