From 3fde3154fc5263656c31a852328e91586ebb3c39 Mon Sep 17 00:00:00 2001
From: RavSinghChandan <ravchandan15@gmail.com>
Date: Fri, 30 Oct 2026 22:21:41 +0530
Subject: [PATCH] Return None instead of crashing on an invalid alpha in color5

---
 tests/test_tinycss2.py | 9 +++++++++
 tinycss2/color5.py     | 6 ++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/tests/test_tinycss2.py b/tests/test_tinycss2.py
index 98fbf7c..1e081d8 100644
--- a/tests/test_tinycss2.py
+++ b/tests/test_tinycss2.py
@@ -218,6 +218,15 @@ def test_color_currentcolor_5():
         assert parse_color5(value) == 'currentcolor'
 
 
+@pytest.mark.parametrize('input', [
+    'device-cmyk(0 0 0 0 / foo)',
+    'device-cmyk(0 0 0 0 / 1 2)',
+    'color(--custom 1 0 0 / foo)',
+])
+def test_color_invalid_alpha_5(input):
+    assert parse_color5(input) is None
+
+
 @json_test()
 def test_color_function_4(input):
     return _build_color(parse_color4(input))
diff --git a/tinycss2/color5.py b/tinycss2/color5.py
index b9d0066..3354453 100644
--- a/tinycss2/color5.py
+++ b/tinycss2/color5.py
@@ -70,10 +70,12 @@ def parse_color(input, color_schemes=None):
                     tokens = tokens[:index]
                     break
 
+        if (alpha := color4._parse_alpha(alpha)) is None:
+            return
         if name == 'device-cmyk':
-            return _parse_device_cmyk(tokens, color4._parse_alpha(alpha), old_syntax)
+            return _parse_device_cmyk(tokens, alpha, old_syntax)
         elif name == 'color':
-            return _parse_color(space, tokens, color4._parse_alpha(alpha))
+            return _parse_color(space, tokens, alpha)
         elif name == 'light-dark':
             return _parse_light_dark(tokens, color_scheme)
         else: