diff --git a/exp/hough.py b/exp/hough.py
--- a/exp/hough.py
+++ b/exp/hough.py
@@ -98,7 +98,7 @@ class HoughTransform:
 		(x0,y0)=self._center
 		(dx,dy)=(x-x0,y0-y)
 		d=dx*math.cos(alphaRad)+dy*math.sin(alphaRad)
-		return round(d)
+		return int(d)
 
 	def _detectLines(self):
 		bag=LineBag()