diff --git a/.npmignore b/.npmignore
index f9680ba..0d09332 100644
--- a/.npmignore
+++ b/.npmignore
@@ -4,6 +4,10 @@ node_modules/
 coverage/
 test/
 typings/
+src/
+tsconfig.json
+tslint.json
+typings.json
 
 npm-debug.log
 .eslintrc
@@ -12,3 +16,6 @@ npm-debug.log
 .travis.yml
 
 CONTRIBUTING.md
+
+*.spec.js
+*.spec.ts
diff --git a/package.json b/package.json
index 8e83b78..052585e 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,9 @@
   "description": "Bot Core package to run bots",
   "main": "lib/index.js",
   "typings": "lib/index.d.ts",
+  "files": [
+    "lib"
+  ],
   "scripts-info": {
     "info": "List available scripts",
     "build": "Builds the plugin, by cleaning and compiling TypesScript into Javascript",
diff --git a/src/loader.ts b/src/loader.ts
index 77abf31..f5022c3 100644
--- a/src/loader.ts
+++ b/src/loader.ts
@@ -33,8 +33,7 @@ export class PluginLoader {
     protected requireLibrary(libpath: string): BotBuilder.Library {
         let lib = require(libpath).default as BotBuilder.Library;
 
-        // XXX this validation could be improved checking that lib instanceof BotBuilder.Library
-        if (!lib.name) {
+        if (!(lib instanceof BotBuilder.Library)) {
             logger.warn(`Skip plugin at ${libpath}: not a valid Library`);
             return null;
         }