diff --git a/data-url/Cargo.toml b/data-url/Cargo.toml
index e91fd6b4..cdde4ac9 100644
--- a/data-url/Cargo.toml
+++ b/data-url/Cargo.toml
@@ -17,6 +17,7 @@ alloc = []
 
 [dev-dependencies]
 tester = "0.9"
+# We pin this transitive dev dep so that MSRV CI can continue to run.
 unicode-width = "=0.1.12"
 serde = {version = "1.0", features = ["derive"]}
 serde_json = "1.0"