diff --git a/crates/winnow-datetime-assert/Cargo.toml b/crates/winnow-datetime-assert/Cargo.toml
index 8faac81..c464f09 100644
--- a/crates/winnow-datetime-assert/Cargo.toml
+++ b/crates/winnow-datetime-assert/Cargo.toml
@@ -13,7 +13,7 @@ readme = "README.md"
 edition = "2021"
 
 [dependencies]
-winnow_datetime = { path = "../winnow-datetime", version = "0.1.0" }
+winnow_datetime = { path = "../winnow-datetime", version = "0.1.0",  features = ["serde"] }
 libtest-mimic = "0.8.1"
 galvanic-test = "0.2.0"
 winnow = "0.6.20"