diff --git a/skimage/filter/rank/_percentile.py b/skimage/filter/rank/_percentile.py
index b87ef5b2..f8ace8a4 100644
--- a/skimage/filter/rank/_percentile.py
+++ b/skimage/filter/rank/_percentile.py
@@ -323,7 +323,8 @@ def sum_percentile(image, selem, out=None, mask=None, shift_x=False,
 
     Only greyvalues between percentiles [p0, p1] are considered in the filter.
 
-    Note that the result is truncated to 8 or 16 bit.
+    Note that the sum may overflow depending on the data type of the input
+    array.
 
     Parameters
     ----------
diff --git a/skimage/filter/rank/bilateral.py b/skimage/filter/rank/bilateral.py
index 4f36e628..d01680db 100644
--- a/skimage/filter/rank/bilateral.py
+++ b/skimage/filter/rank/bilateral.py
@@ -174,6 +174,9 @@ def sum_bilateral(image, selem, out=None, mask=None, shift_x=False,
     Only pixels belonging to the structuring element AND having a greylevel
     inside this interval are summed.
 
+    Note that the sum may overflow depending on the data type of the input
+    array.
+
     Parameters
     ----------
     image : 2-D array (uint8, uint16)
diff --git a/skimage/filter/rank/generic.py b/skimage/filter/rank/generic.py
index d46c7436..ccc1166e 100644
--- a/skimage/filter/rank/generic.py
+++ b/skimage/filter/rank/generic.py
@@ -578,6 +578,9 @@ def pop(image, selem, out=None, mask=None, shift_x=False, shift_y=False):
 def sum(image, selem, out=None, mask=None, shift_x=False, shift_y=False):
     """Return the local sum of pixels.
 
+    Note that the sum may overflow depending on the data type of the input
+    array.
+
     Parameters
     ----------
     image : 2-D array (uint8, uint16)