diff --git a/skimage/filter/__init__.py b/skimage/filter/__init__.py
index bd9c94cc..5479af5d 100644
--- a/skimage/filter/__init__.py
+++ b/skimage/filter/__init__.py
@@ -2,7 +2,8 @@ from .lpi_filter import *
 from .ctmf import median_filter
 from ._canny import canny
 from .edges import (sobel, hsobel, vsobel, scharr, hscharr, vscharr, prewitt,
-                    hprewitt, vprewitt, roberts , roberts_positive_diagonal, roberts_negative_diagonal)
+                    hprewitt, vprewitt, roberts , roberts_positive_diagonal,
+                    roberts_negative_diagonal)
 from ._denoise import denoise_tv_chambolle, tv_denoise
 from ._denoise_cy import denoise_bilateral, denoise_tv_bregman
 from ._rank_order import rank_order
diff --git a/skimage/filter/edges.py b/skimage/filter/edges.py
index 0e1fcda0..05404615 100644
--- a/skimage/filter/edges.py
+++ b/skimage/filter/edges.py
@@ -357,7 +357,8 @@ def roberts(image, mask=None):
     output : ndarray
         The Roberts' Cross edge map.
     """
-    return np.sqrt(roberts_positive_diagonal(image, mask)**2 + roberts_negative_diagonal(image, mask)**2)
+    return np.sqrt(roberts_positive_diagonal(image, mask)**2 +\
+                   roberts_negative_diagonal(image, mask)**2)
 
 
 def roberts_positive_diagonal(image, mask=None):