diff --git a/tests/02_rayon.py b/tests/02_rayon.py
index d3389e7f53cdc89f67fffea9df4ae5dee2900879..a9a0fc4ab6c1b0e3aa70e50956d53fe2143ccc4d 100644
--- a/tests/02_rayon.py
+++ b/tests/02_rayon.py
@@ -10,7 +10,7 @@ c = Camera(100, 200, 3)
 
 r_center = c.ray_at(c.image_nrows / 2, c.image_ncols / 2);
 
-assert (abs(r_center.direction*Vector([0,0,1]) - r_center.direction.norm()) < 0.01, "c.ray_at(c.image_nrows / 2, c.image_ncols / 2) should have the direction [0,0,1].")
+assert abs(r_center.direction*Vector([0,0,1]) - r_center.direction.norm()) < 0.01, "c.ray_at(c.image_nrows / 2, c.image_ncols / 2) should have the direction [0,0,1]."
 
 r_zero = c.ray_at(0,0);