diff --git a/relay/kusama/Cargo.toml b/relay/kusama/Cargo.toml
index 6f4a7be8f1..744220a846 100644
--- a/relay/kusama/Cargo.toml
+++ b/relay/kusama/Cargo.toml
@@ -11,7 +11,7 @@ parity-scale-codec = { version = "3.1.5", default-features = false, features = [
 scale-info = { version = "2.1.2", default-features = false, features = ["derive"] }
 log = { version = "0.4.17", default-features = false }
 rustc-hex = { version = "2.1.0", default-features = false }
-serde = { version = "1.0.137", default-features = false }
+serde = { version = "1.0.139", default-features = false }
 serde_derive = { version = "1.0.117", optional = true }
 static_assertions = "1.1.0"
 smallvec = "1.8.0"
diff --git a/relay/polkadot/Cargo.toml b/relay/polkadot/Cargo.toml
index 99b8629a20..941171392d 100644
--- a/relay/polkadot/Cargo.toml
+++ b/relay/polkadot/Cargo.toml
@@ -11,7 +11,7 @@ parity-scale-codec = { version = "3.1.5", default-features = false, features = [
 scale-info = { version = "2.1.2", default-features = false, features = ["derive"] }
 log = { version = "0.4.17", default-features = false }
 rustc-hex = { version = "2.1.0", default-features = false }
-serde = { version = "1.0.137", default-features = false }
+serde = { version = "1.0.139", default-features = false }
 serde_derive = { version = "1.0.117", optional = true }
 static_assertions = "1.1.0"
 smallvec = "1.8.0"