diff --git a/skimage/filters/thresholding.py b/skimage/filters/thresholding.py
index 331ea3f4..d21bd579 100644
--- a/skimage/filters/thresholding.py
+++ b/skimage/filters/thresholding.py
@@ -133,7 +133,7 @@ def threshold_otsu(image, nbins=256):
 
     # Check if the image is multi-colored or not
     if image.min() == image.max():
-        raise TypeError("threshold_otsu is expected to work with images " \
+        raise ValueError("threshold_otsu is expected to work with images " \
                         "having more than one color. The input image seems " \
                         "to have just one color {0}.".format(image.min()))