diff --git a/elodie/media/media.py b/elodie/media/media.py
index e65ac2a..704255c 100644
--- a/elodie/media/media.py
+++ b/elodie/media/media.py
@@ -295,6 +295,9 @@ class Media(object):
 
     @classmethod
     def get_class_by_file(cls, _file, classes):
+        if not isinstance(_file, basestring) or not os.path.isfile(_file):
+            return None
+
         extension = os.path.splitext(_file)[1][1:].lower()
 
         for i in classes:
diff --git a/elodie/tests/files/.DS_Store b/elodie/tests/files/.DS_Store
new file mode 100644
index 0000000..5008ddf
Binary files /dev/null and b/elodie/tests/files/.DS_Store differ
diff --git a/elodie/tests/media/media_test.py b/elodie/tests/media/media_test.py
index 3658b7a..ef7abaf 100644
--- a/elodie/tests/media/media_test.py
+++ b/elodie/tests/media/media_test.py
@@ -43,11 +43,24 @@ def test_get_class_by_file_unsupported():
 
     assert media is None
 
-def test_get_class_by_file_empty():
+def test_get_class_by_file_ds_store():
     media = Media.get_class_by_file(helper.get_file('.DS_Store'),
                                     [Photo, Video, Audio])
     assert media is None
 
+def test_get_class_by_file_invalid_type():
+    media = Media.get_class_by_file(None,
+                                    [Photo, Video, Audio])
+    assert media is None
+
+    media = Media.get_class_by_file(False,
+                                    [Photo, Video, Audio])
+    assert media is None
+
+    media = Media.get_class_by_file(True,
+                                    [Photo, Video, Audio])
+    assert media is None
+
 def is_valid():
     media = Media()