diff --git a/src/LinkManyBehavior.php b/src/LinkManyBehavior.php
index 2d2ddb3..09f10e6 100644
--- a/src/LinkManyBehavior.php
+++ b/src/LinkManyBehavior.php
@@ -4,6 +4,7 @@
 
 use Yii;
 use yii\base\Behavior;
+use yii\base\InvalidArgumentException;
 use yii\base\InvalidConfigException;
 use yii\base\UnknownPropertyException;
 use yii\db\ActiveRecord;
@@ -123,7 +124,7 @@ public function afterValidate()
             }
 
             $errors = [];
-            $models = isset($this->_inserteds[$name]) ? $this->_inserteds[$name] : [];
+            $models =  ArrayHelper::getValue($this->_inserteds, $name, []);
 
             foreach ($models as $model) {
                 if (!$model->validate()) {
@@ -149,6 +150,10 @@ public function __set($name, $value)
         try {
             parent::__set($name, $value);
         } catch (UnknownPropertyException $exception) {
+            if (!is_array($value)) {
+                throw new InvalidArgumentException("The '$name' property must be an array");
+            }
+
             $definition = $this->findDefinition($name);
             if ($definition !== null) {
                 $this->prepareRelation($definition, [$name => $value]);
diff --git a/tests/LinkManyBehaviorTest.php b/tests/LinkManyBehaviorTest.php
index f9b4677..dea56cc 100644
--- a/tests/LinkManyBehaviorTest.php
+++ b/tests/LinkManyBehaviorTest.php
@@ -4,36 +4,41 @@
 
 use solutosoft\linkmany\LinkManyBehavior;
 use solutosoft\linkmany\tests\models\Post;
-use solutosoft\linkmany\tests\models\Tag;
 
-//use solutosoft\linkmany\tests\models\PostLanguage;
-//use solutosoft\linkmany\tests\models\Tag;
 
 class LinkManyBehaviorTest extends TestCase
 {
-    public function testInitException()
+    public function testInitSuccess()
     {
-        $this->setExpectedException('\yii\base\InvalidConfigException');
-
         new LinkManyBehavior([
             'relations' => [
-                ['invalid' => true]
+                'relation_1',
+                'relation_2' => [
+                    'formName' => 'test'
+                ]
             ]
         ]);
     }
 
-    public function testInitSuccess()
+    public function testInitException()
     {
+        $this->setExpectedException('\yii\base\InvalidConfigException');
+
         new LinkManyBehavior([
             'relations' => [
-                'relation_1',
-                'relation_2' => [
-                    'formName' => 'test'
-                ]
+                ['invalid' => true]
             ]
         ]);
     }
 
+    public function testInvalidRelationValue()
+    {
+        $this->setExpectedException('\yii\base\InvalidArgumentException');
+
+        $post = new Post();
+        $post->comments = null;
+    }
+
     public function testFillNewRecord()
     {
         $post = new Post();
@@ -234,6 +239,7 @@ public function testSetRelation()
         $post->tags = [1];
 
         $post->save();
+        $post->refresh();
         $this->assertCount(1, $post->tags);
     }
 }
\ No newline at end of file