diff --git a/skimage/morphology/cmorph.pyx b/skimage/morphology/cmorph.pyx
index a09a39a3..05dba333 100644
--- a/skimage/morphology/cmorph.pyx
+++ b/skimage/morphology/cmorph.pyx
@@ -8,7 +8,7 @@ cimport numpy as np
 from libc.stdlib cimport malloc, free
 
 
-def dilate(np.ndarray[np.uint8_t, ndim=2] image,
+def _dilate(np.ndarray[np.uint8_t, ndim=2] image,
            np.ndarray[np.uint8_t, ndim=2] selem,
            np.ndarray[np.uint8_t, ndim=2] out=None,
            char shift_x=0, char shift_y=0):
@@ -63,7 +63,7 @@ def dilate(np.ndarray[np.uint8_t, ndim=2] image,
     return out
 
 
-def erode(np.ndarray[np.uint8_t, ndim=2] image,
+def _erode(np.ndarray[np.uint8_t, ndim=2] image,
           np.ndarray[np.uint8_t, ndim=2] selem,
           np.ndarray[np.uint8_t, ndim=2] out=None,
           char shift_x=0, char shift_y=0):
diff --git a/skimage/morphology/grey.py b/skimage/morphology/grey.py
index 2cca69b6..233bca4a 100644
--- a/skimage/morphology/grey.py
+++ b/skimage/morphology/grey.py
@@ -58,7 +58,7 @@ def erosion(image, selem, out=None, shift_x=False, shift_y=False):
         raise NotImplementedError("In-place erosion not supported!")
     image = img_as_ubyte(image)
     selem = img_as_ubyte(selem)
-    return cmorph.erode(image, selem, out=out,
+    return cmorph._erode(image, selem, out=out,
                         shift_x=shift_x, shift_y=shift_y)
 
 
@@ -111,7 +111,7 @@ def dilation(image, selem, out=None, shift_x=False, shift_y=False):
         raise NotImplementedError("In-place dilation not supported!")
     image = img_as_ubyte(image)
     selem = img_as_ubyte(selem)
-    return cmorph.dilate(image, selem, out=out,
+    return cmorph._dilate(image, selem, out=out,
                          shift_x=shift_x, shift_y=shift_y)