diff --git a/test/test_testing.py b/test/test_testing.py
index c33285bd..fd9f1b6a 100644
--- a/test/test_testing.py
+++ b/test/test_testing.py
@@ -142,7 +142,10 @@ def test_failing_test(tmp_path):
                 # problems with this, so let's check that.
                 "CIBW_MANYLINUX_I686_IMAGE": "manylinux1",
                 "CIBW_MANYLINUX_X86_64_IMAGE": "manylinux1",
-                # tests don't run on CPython 3.8 when running on macOS arm64
+                # CPython 3.8 when running on macOS arm64 is unusual. The build
+                # always runs in x86_64, so the arm64 tests are not run. See
+                # #1169 for reasons why. That means the build succeeds, which
+                # we don't want. So we skip that build.
                 "CIBW_SKIP": "cp38-macosx_arm64",
             },
         )