diff --git a/src/Phpml/ModelManager.php b/src/Phpml/ModelManager.php
index 2ba8cc2..c03d0ed 100644
--- a/src/Phpml/ModelManager.php
+++ b/src/Phpml/ModelManager.php
@@ -4,25 +4,26 @@ declare(strict_types=1);
 
 namespace Phpml;
 
-use Phpml\Estimator;
 use Phpml\Exception\SerializeException;
 use Phpml\Exception\FileException;
 
 class ModelManager
 {
     /**
-     * @param Estimator     $object
-     * @param string        $filepath
+     * @param Estimator $estimator
+     * @param string $filepath
+     * @throws FileException
+     * @throws SerializeException
      */
-    public function saveToFile(Estimator $object, string $filepath)
+    public function saveToFile(Estimator $estimator, string $filepath)
     {
-        if (!file_exists($filepath) || !is_writable(dirname($filepath))) {
+        if (!is_writable(dirname($filepath))) {
             throw FileException::cantSaveFile(basename($filepath));
         }
 
-        $serialized = serialize($object);
+        $serialized = serialize($estimator);
         if (empty($serialized)) {
-            throw SerializeException::cantSerialize(get_type($object));
+            throw SerializeException::cantSerialize(get_type($estimator));
         }
 
         $result = file_put_contents($filepath, $serialized, LOCK_EX);
@@ -33,10 +34,11 @@ class ModelManager
 
     /**
      * @param string $filepath
-     *
      * @return Estimator
+     * @throws FileException
+     * @throws SerializeException
      */
-    public function restoreFromFile(string $filepath)
+    public function restoreFromFile(string $filepath) : Estimator
     {
         if (!file_exists($filepath) || !is_readable($filepath)) {
             throw FileException::cantOpenFile(basename($filepath));
diff --git a/tests/Phpml/ModelManagerTest.php b/tests/Phpml/ModelManagerTest.php
index e5d7f5e..066aad1 100644
--- a/tests/Phpml/ModelManagerTest.php
+++ b/tests/Phpml/ModelManagerTest.php
@@ -12,27 +12,15 @@ class ModelManagerTest extends TestCase
 {
     public function testSaveAndRestore()
     {
-        $filename = 'test-save-to-file-'.rand(100, 999).'-'.uniqid();
-        $filepath = tempnam(sys_get_temp_dir(), $filename);
+        $filename = uniqid();
+        $filepath = sys_get_temp_dir() . DIRECTORY_SEPARATOR . $filename;
 
-        $obj = new LeastSquares();
+        $estimator = new LeastSquares();
         $modelManager = new ModelManager();
-        $modelManager->saveToFile($obj, $filepath);
+        $modelManager->saveToFile($estimator, $filepath);
 
         $restored = $modelManager->restoreFromFile($filepath);
-        $this->assertEquals($obj, $restored);
-    }
-
-    /**
-     * @expectedException \Phpml\Exception\FileException
-     */
-    public function testSaveToWrongFile()
-    {
-        $filepath = sys_get_temp_dir() . DIRECTORY_SEPARATOR . 'unexisting';
-
-        $obj = new LeastSquares();
-        $modelManager = new ModelManager();
-        $modelManager->saveToFile($obj, $filepath);
+        $this->assertEquals($estimator, $restored);
     }
 
     /**