diff --git a/.gitignore b/.gitignore
index 06a1377de..0ee4b2d1d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -88,3 +88,4 @@ compile_commands.json
 .cache
 rust-project.json
 **/tmp
+# Cache-test marker; this comment intentionally has no ignore rule.