diff --git a/kupyna/Cargo.toml b/kupyna/Cargo.toml
index 9fd8eb9f..0b50603d 100644
--- a/kupyna/Cargo.toml
+++ b/kupyna/Cargo.toml
@@ -16,6 +16,7 @@ rust-version = "1.71"
 digest = { version = "=0.11.0-pre.9", default-features = false, features = ["core-api"] }
 
 [dev-dependencies]
+hex-literal = "0.4.1"
 
 [features]
 default = ["std"]