diff --git a/scrapy/tests/test_pipeline_images.py b/scrapy/tests/test_pipeline_images.py
index 2b0a81526..03871383e 100644
--- a/scrapy/tests/test_pipeline_images.py
+++ b/scrapy/tests/test_pipeline_images.py
@@ -6,13 +6,15 @@ from shutil import rmtree
 from twisted.trial import unittest
 
 
+skip = False
 try:
     from PIL import Image
 except ImportError, e:
-    skip = True
+    skip = 'Missing Python Imaging Library, install https://pypi.python.org/pypi/Pillow'
 else:
     encoders = set(('jpeg_encoder', 'jpeg_decoder'))
-    skip = not encoders.issubset(set(Image.core.__dict__))
+    if not encoders.issubset(set(Image.core.__dict__)):
+        skip = 'Missing JPEG encoders'
 
 def _mocked_download_func(request, info):
     response = request.meta.get('response')
@@ -49,7 +51,7 @@ class ImagesPipelineTestCase(unittest.TestCase):
     def test_thumbnail_name(self):
         thumbnail_name = self.pipeline.thumb_key
         name = '50'
-        self.assertEqual(thumbnail_name("/tmp/foo.jpg", name),  
+        self.assertEqual(thumbnail_name("/tmp/foo.jpg", name),
                          'thumbs/50/271f172bb4727281011c80fe763e93a47bb6b3fe.jpg')
         self.assertEqual(thumbnail_name("foo.png", name),
                          'thumbs/50/0945c699b5580b99e4f40dffc009699b2b6830a7.jpg')