diff --git a/skimage/filters/rank/bilateral.py b/skimage/filters/rank/bilateral.py
index 48e350b8..fa124d05 100644
--- a/skimage/filters/rank/bilateral.py
+++ b/skimage/filters/rank/bilateral.py
@@ -111,7 +111,7 @@ def pop_bilateral(image, selem, out=None, mask=None, shift_x=False,
 
 
     The number of pixels is defined as the number of pixels which are included
-    in the structuring element and the mask. Additionally the must have a
+    in the structuring element and the mask. Additionally pixels must have a
     greylevel inside the interval [g-s0, g+s1] where g is the greyvalue of the
     center pixel.