diff --git a/skimage/measure/_regionprops.py b/skimage/measure/_regionprops.py
index 08005a4e..32356a4a 100644
--- a/skimage/measure/_regionprops.py
+++ b/skimage/measure/_regionprops.py
@@ -109,7 +109,7 @@ class _RegionProperties(object):
     def __init__(self, slice, label, label_image, intensity_image,
                  cache_active):
                  
-        if not intensity_image is None:
+        if intensity_image is not None:
             if not intensity_image.shape == label_image.shape:
                 raise ValueError('Label and intensity image must be the same shape.')