diff --git a/manimlib/mobject/geometry.py b/manimlib/mobject/geometry.py
index 407841a0..a2adf25c 100644
--- a/manimlib/mobject/geometry.py
+++ b/manimlib/mobject/geometry.py
@@ -918,10 +918,9 @@ class Polygon(VMobject):
     def __init__(
         self,
         *vertices: Vect3,
-        flat_stroke: bool = True,
         **kwargs
     ):
-        super().__init__(flat_stroke=flat_stroke, **kwargs)
+        super().__init__(**kwargs)
         self.set_points_as_corners([*vertices, vertices[0]])
 
     def get_vertices(self) -> Vect3Array:
@@ -967,10 +966,9 @@ class Polyline(VMobject):
     def __init__(
         self,
         *vertices: Vect3,
-        flat_stroke: bool = True,
         **kwargs
     ):
-        super().__init__(flat_stroke=flat_stroke, **kwargs)
+        super().__init__(**kwargs)
         self.set_points_as_corners(vertices)