diff --git a/skimage/filter/rank/generic.py b/skimage/filter/rank/generic.py
index b7293862..703b66b3 100644
--- a/skimage/filter/rank/generic.py
+++ b/skimage/filter/rank/generic.py
@@ -556,10 +556,10 @@ def sum(image, selem, out=None, mask=None, shift_x=False, shift_y=False):
     >>> from skimage.morphology import square
     >>> import skimage.filter.rank as rank
     >>> ima = np.array([[0, 0, 0, 0, 0],
-    ...                       [0, 1, 1, 1, 0],
-    ...                       [0, 1, 1, 1, 0],
-    ...                       [0, 1, 1, 1, 0],
-    ...                       [0, 0, 0, 0, 0]], dtype=np.uint8)
+    ...                 [0, 1, 1, 1, 0],
+    ...                 [0, 1, 1, 1, 0],
+    ...                 [0, 1, 1, 1, 0],
+    ...                 [0, 0, 0, 0, 0]], dtype=np.uint8)
     >>> rank.sum(ima, square(3))
     array([[1, 2, 3, 2, 1],
            [2, 4, 6, 4, 2],
diff --git a/skimage/filter/rank/generic_cy.pyx b/skimage/filter/rank/generic_cy.pyx
index dd461fc7..2a1a8455 100644
--- a/skimage/filter/rank/generic_cy.pyx
+++ b/skimage/filter/rank/generic_cy.pyx
@@ -471,10 +471,10 @@ def _pop(dtype_t[:, ::1] image,
           shift_x, shift_y, 0, 0, 0, 0, max_bin)
 
 def _sum(dtype_t[:, ::1] image,
-                   char[:, ::1] selem,
-                   char[:, ::1] mask,
-                   dtype_t_out[:, ::1] out,
-                   char shift_x, char shift_y, Py_ssize_t max_bin):
+         char[:, ::1] selem,
+         char[:, ::1] mask,
+         dtype_t_out[:, ::1] out,
+         char shift_x, char shift_y, Py_ssize_t max_bin):
 
     _core(_kernel_sum[dtype_t], image, selem, mask,
           out, shift_x, shift_y, 0, 0, 0, 0, max_bin)
diff --git a/skimage/filter/rank/percentile_cy.pyx b/skimage/filter/rank/percentile_cy.pyx
index bd0cbe53..38d04b33 100644
--- a/skimage/filter/rank/percentile_cy.pyx
+++ b/skimage/filter/rank/percentile_cy.pyx
@@ -91,9 +91,9 @@ cdef inline double _kernel_mean(Py_ssize_t* histo, double pop, dtype_t g,
         return 0
 
 cdef inline double _kernel_sum(Py_ssize_t* histo, double pop, dtype_t g,
-                                Py_ssize_t max_bin, Py_ssize_t mid_bin,
-                                double p0, double p1,
-                                Py_ssize_t s0, Py_ssize_t s1):
+                               Py_ssize_t max_bin, Py_ssize_t mid_bin,
+                               double p0, double p1,
+                               Py_ssize_t s0, Py_ssize_t s1):
 
     cdef Py_ssize_t i, sum, sum_g, n
 
@@ -269,11 +269,11 @@ def _mean(dtype_t[:, ::1] image,
           shift_x, shift_y, p0, p1, 0, 0, max_bin)
 
 def _sum(dtype_t[:, ::1] image,
-          char[:, ::1] selem,
-          char[:, ::1] mask,
-          dtype_t_out[:, ::1] out,
-          char shift_x, char shift_y, double p0, double p1,
-          Py_ssize_t max_bin):
+         char[:, ::1] selem,
+         char[:, ::1] mask,
+         dtype_t_out[:, ::1] out,
+         char shift_x, char shift_y, double p0, double p1,
+         Py_ssize_t max_bin):
 
     _core(_kernel_sum[dtype_t], image, selem, mask, out,
           shift_x, shift_y, p0, p1, 0, 0, max_bin)