diff --git a/skimage/util/process.py b/skimage/util/process.py
index e0463fec..c03b1c5b 100644
--- a/skimage/util/process.py
+++ b/skimage/util/process.py
@@ -27,7 +27,8 @@ def _get_chunks(shape, ncpu):
     return tuple(chunks)
 
 
-def process_chunks(function, array, args=(), kwargs={} chunks=None, depth=0, mode=None):
+def process_chunks(function, array, args=(), kwargs={}, chunks=None, depth=0,
+                   mode=None):
     """Map a function in parallel across an array.
 
     Split an array into possibly overlapping chunks of a given depth and
@@ -56,7 +57,7 @@ def process_chunks(function, array, args=(), kwargs={} chunks=None, depth=0, mod
     a chunk.
 
     """
-    if chunks == None:
+    if chunks is None:
         shape = array.shape
         ncpu = cpu_count()
         chunks = _get_chunks(shape, ncpu)
diff --git a/skimage/util/tests/test_process.py b/skimage/util/tests/test_process.py
index 3710cece..52fe248c 100644
--- a/skimage/util/tests/test_process.py
+++ b/skimage/util/tests/test_process.py
@@ -4,6 +4,7 @@ from numpy.testing import assert_array_almost_equal
 from skimage.filters import threshold_adaptive, gaussian_filter
 from skimage.util import process_chunks
 
+
 def test_process_chunks():
     # data
     a = np.arange(144).reshape(12, 12).astype(float)
@@ -31,6 +32,7 @@ def test_process_chunks():
 
 def test_no_chunks():
     a = np.ones(1 * 4 * 8 * 9).reshape(1, 4, 8, 9)
+
     def add_42(arr):
         return arr + 42