diff --git a/bridges/primitives/chain-millau/Cargo.toml b/bridges/primitives/chain-millau/Cargo.toml
index b422e1545d670c3506a4ac1e970eb0ea6e314032..c58800b63c9101275fe536549cea7d9419edb89e 100644
--- a/bridges/primitives/chain-millau/Cargo.toml
+++ b/bridges/primitives/chain-millau/Cargo.toml
@@ -16,7 +16,7 @@ bp-runtime = { path = "../runtime", default-features = false }
 fixed-hash = { version = "0.7.0", default-features = false }
 hash256-std-hasher = { version = "0.15.2", default-features = false }
 impl-codec = { version = "0.6", default-features = false }
-impl-serde = { version = "0.3.1", optional = true }
+impl-serde = { version = "0.4.0", optional = true }
 parity-util-mem = { version = "0.12", default-features = false, features = ["primitive-types"] }
 scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
 serde = { version = "1.0", optional = true, features = ["derive"] }