diff --git a/Cargo.toml b/Cargo.toml
index 43077836..b374c8f8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,8 +32,8 @@ hyperlane_resources = { path = "resources", version = "23.0.36" }
 hyperlane_application = { path = "application", version = "23.0.36" }
 
 tracing = "0.1.44"
-hyperlane = "21.3.6"
-hyperlane-core = "21.7.6"
+hyperlane = "21.12.0"
+hyperlane-core = "21.12.0"
 hyperlane-utils = "33.1.14"
 serde = { version = "1.0.229", features = ["derive"] }
 
diff --git a/application/middleware/request/const.rs b/application/middleware/request/const.rs
new file mode 100644
index 00000000..c4639a0f
--- /dev/null
+++ b/application/middleware/request/const.rs
@@ -0,0 +1,2 @@
+/// HTTP `date` header name, lowercased per HTTP/2 convention.
+pub(crate) const DATE: &str = "date";
diff --git a/application/middleware/request/mod.rs b/application/middleware/request/mod.rs
index 4dfc79f4..f17857ff 100644
--- a/application/middleware/request/mod.rs
+++ b/application/middleware/request/mod.rs
@@ -1,6 +1,9 @@
+mod r#const;
 mod r#impl;
 mod r#struct;
 
 pub use r#struct::*;
 
+pub(crate) use r#const::*;
+
 use super::*;