diff --git a/skimage/draw/setup.py b/skimage/draw/setup.py
index 5b8e237d..1414fca8 100644
--- a/skimage/draw/setup.py
+++ b/skimage/draw/setup.py
@@ -15,7 +15,7 @@ def configuration(parent_package='', top_path=None):
     cython(['_draw.pyx'], working_path=base_path)
 
     config.add_extension('_draw', sources=['_draw.c'],
-                         include_dirs=[get_numpy_include_dirs(), '../shared'])
+                         include_dirs=[get_numpy_include_dirs(), '../_shared'])
 
     return config
 
diff --git a/skimage/filter/rank/_crank16.pyx b/skimage/filter/rank/_crank16.pyx
index e81bf81f..b7aca483 100644
--- a/skimage/filter/rank/_crank16.pyx
+++ b/skimage/filter/rank/_crank16.pyx
@@ -5,7 +5,7 @@
 
 import numpy as np
 cimport numpy as np
-from libc.math cimport log2
+from libc.math cimport log
 from skimage.filter.rank._core16 cimport _core16
 
 
@@ -274,7 +274,7 @@ cdef inline np.uint16_t kernel_entropy(Py_ssize_t * histo, float pop,
         for i in range(maxbin):
             p = histo[i] / pop
             if p > 0:
-                e -= p * log2(p)
+                e -= p * log(p) / 0.30102999566398119521373889472449
 
         return < np.uint16_t > e * 1000
     else:
diff --git a/skimage/filter/rank/_crank8.pyx b/skimage/filter/rank/_crank8.pyx
index 8bff9703..d7ece4dd 100644
--- a/skimage/filter/rank/_crank8.pyx
+++ b/skimage/filter/rank/_crank8.pyx
@@ -5,7 +5,7 @@
 
 import numpy as np
 cimport numpy as np
-from libc.math cimport log2
+from libc.math cimport log
 from skimage.filter.rank._core8 cimport _core8
 
 
@@ -279,7 +279,7 @@ cdef inline np.uint8_t kernel_entropy(Py_ssize_t * histo, float pop,
         for i in range(256):
             p = histo[i] / pop
             if p > 0:
-                e -= p * log2(p)
+                e -= p * log(p) / 0.30102999566398119521373889472449
 
         return < np.uint8_t > e * 10
     else:
diff --git a/skimage/filter/setup.py b/skimage/filter/setup.py
index 650a26a6..934d3f2e 100644
--- a/skimage/filter/setup.py
+++ b/skimage/filter/setup.py
@@ -29,31 +29,31 @@ def configuration(parent_package='', top_path=None):
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension('_denoise_cy', sources=['_denoise_cy.c'],
         include_dirs=[get_numpy_include_dirs(), '../_shared'])
-    config.add_extension('rank/_core8', sources=['rank/_core8.c'],
+    config.add_extension('rank._core8', sources=['rank/_core8.c'],
         include_dirs=[get_numpy_include_dirs()])
-    config.add_extension('rank/_core16', sources=['rank/_core16.c'],
+    config.add_extension('rank._core16', sources=['rank/_core16.c'],
         include_dirs=[get_numpy_include_dirs()])
-    config.add_extension('rank/_crank8', sources=['rank/_crank8.c'],
+    config.add_extension('rank._crank8', sources=['rank/_crank8.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/_crank8_percentiles', sources=['rank/_crank8_percentiles.c'],
+        'rank._crank8_percentiles', sources=['rank/_crank8_percentiles.c'],
         include_dirs=[get_numpy_include_dirs()])
-    config.add_extension('rank/_crank16', sources=['rank/_crank16.c'],
+    config.add_extension('rank._crank16', sources=['rank/_crank16.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/_crank16_percentiles', sources=['rank/_crank16_percentiles.c'],
+        'rank._crank16_percentiles', sources=['rank/_crank16_percentiles.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/_crank16_bilateral', sources=['rank/_crank16_bilateral.c'],
+        'rank._crank16_bilateral', sources=['rank/_crank16_bilateral.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/rank', sources=['rank/rank.c'],
+        'rank.rank', sources=['rank/rank.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/percentile_rank', sources=['rank/percentile_rank.c'],
+        'rank.percentile_rank', sources=['rank/percentile_rank.c'],
         include_dirs=[get_numpy_include_dirs()])
     config.add_extension(
-        'rank/bilateral_rank', sources=['rank/bilateral_rank.c'],
+        'rank.bilateral_rank', sources=['rank/bilateral_rank.c'],
         include_dirs=[get_numpy_include_dirs()])
 
     return config