diff --git a/lib/miro/dominant_colors.rb b/lib/miro/dominant_colors.rb
index 8a819ae..e57713f 100644
--- a/lib/miro/dominant_colors.rb
+++ b/lib/miro/dominant_colors.rb
@@ -113,7 +113,7 @@ def open_downsampled_image
 
     def image_magick_params
       if Miro.histogram?
-        "':in[0]' -resize :resolution -colors :colors -colorspace :quantize -quantize :quantize -alpha remove -format %c histogram:info:"
+        "':in[0]' -resize :resolution -colors :colors -colorspace :quantize -quantize :quantize -alpha remove -alpha off -format %c histogram:info:"
       else
         "':in[0]' -resize :resolution -colors :colors -colorspace :quantize -quantize :quantize :out"
       end