diff --git a/functions.py b/functions.py
index c54155a..23f8002 100644
--- a/functions.py
+++ b/functions.py
@@ -166,7 +166,7 @@ def along_stroke(stroke,attr,length,min,max) :
 
 def randomise_points(mat,points,attr,strength) :
     for point in points :
-        if attr is 'co' :
+        if attr == 'co' :
             random_x = (rand()-0.5)
             random_y = (rand()-0.5)