diff --git a/kitty/fonts/render.py b/kitty/fonts/render.py
index ba03837d6..c739fc7ad 100644
--- a/kitty/fonts/render.py
+++ b/kitty/fonts/render.py
@@ -3,7 +3,7 @@
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
 import ctypes
-from math import sin, pi, ceil, floor
+from math import sin, pi, ceil, floor, sqrt
 
 from kitty.constants import isosx
 from .box_drawing import render_box_char, is_renderable_box_char
@@ -30,16 +30,21 @@ def add_curl(buf, cell_width, position, thickness, cell_height):
     def clamp_y(y):
         return max(0, min(int(y), cell_height - 1))
 
-    for x in range(cell_width):
-        y_exact = yfactor * sin(x * xfactor) + position
+    def clamp_x(x):
+        return max(0, min(int(x), cell_width - 1))
+
+    def add_intensity(x, y, distance):
+        buf[cell_width * y + x] = min(255, buf[cell_width * y + x] + int(255 * (1 - distance)))
+
+    for x_exact in range(cell_width):
+        y_exact = yfactor * sin(x_exact * xfactor) + position
         y_below = clamp_y(floor(y_exact))
         y_above = clamp_y(ceil(y_exact))
-        if y_below == y_above:
-            buf[cell_width * y_below + x] = 255
-            continue
-        for y in (y_below, y_above):
-            intensity = int(255 * (1 - abs(y - y_exact)))
-            buf[cell_width * y + x] = intensity
+        x_before, x_after = map(clamp_x, (x_exact - 1, x_exact + 1))
+        for x in {x_before, x_exact, x_after}:
+            for y in {y_below, y_above}:
+                dist = sqrt((x - x_exact)**2 + (y - y_exact)**2) / 2
+                add_intensity(x, y, dist)
 
 
 def render_cell(text=' ', bold=False, italic=False, underline=0, strikethrough=False):