diff --git a/pygmsh/built_in/spline.py b/pygmsh/built_in/spline.py
index <HASH>..<HASH> 100644
--- a/pygmsh/built_in/spline.py
+++ b/pygmsh/built_in/spline.py
@@ -10,7 +10,7 @@ class Spline(LineBase):
 
         for c in points:
             assert isinstance(c, Point)
-        assert len(control_points) > 1
+        assert len(points) > 1
 
         self.points = points
Spline has points not the control_points of Bspline #<I>