diff --git a/bridges/bin/millau/runtime/src/rialto_messages.rs b/bridges/bin/millau/runtime/src/rialto_messages.rs
index ccca4222f61d..7054382b3852 100644
--- a/bridges/bin/millau/runtime/src/rialto_messages.rs
+++ b/bridges/bin/millau/runtime/src/rialto_messages.rs
@@ -236,7 +236,7 @@ impl messages::BridgedChainWithMessages for Rialto {
 	}
 }
 
-impl TargetHeaderChain<ToRialtoMessagePayload, bp_rialto::AccountId> for Rialto {
+impl TargetHeaderChain<ToRialtoMessagePayload, bp_millau::AccountId> for Rialto {
 	type Error = &'static str;
 	// The proof is:
 	// - hash of the header this proof has been created with;
diff --git a/bridges/bin/millau/runtime/src/rialto_parachain_messages.rs b/bridges/bin/millau/runtime/src/rialto_parachain_messages.rs
index 6840b703f4f4..f26e0d1006ae 100644
--- a/bridges/bin/millau/runtime/src/rialto_parachain_messages.rs
+++ b/bridges/bin/millau/runtime/src/rialto_parachain_messages.rs
@@ -229,9 +229,7 @@ impl messages::BridgedChainWithMessages for RialtoParachain {
 	}
 }
 
-impl TargetHeaderChain<ToRialtoParachainMessagePayload, bp_rialto_parachain::AccountId>
-	for RialtoParachain
-{
+impl TargetHeaderChain<ToRialtoParachainMessagePayload, bp_millau::AccountId> for RialtoParachain {
 	type Error = &'static str;
 	// The proof is:
 	// - hash of the header this proof has been created with;
diff --git a/bridges/bin/rialto-parachain/runtime/src/millau_messages.rs b/bridges/bin/rialto-parachain/runtime/src/millau_messages.rs
index 136b4343c190..96ff18810bcf 100644
--- a/bridges/bin/rialto-parachain/runtime/src/millau_messages.rs
+++ b/bridges/bin/rialto-parachain/runtime/src/millau_messages.rs
@@ -243,7 +243,7 @@ impl messages::BridgedChainWithMessages for Millau {
 	}
 }
 
-impl TargetHeaderChain<ToMillauMessagePayload, bp_millau::AccountId> for Millau {
+impl TargetHeaderChain<ToMillauMessagePayload, bp_rialto_parachain::AccountId> for Millau {
 	type Error = &'static str;
 	// The proof is:
 	// - hash of the header this proof has been created with;
diff --git a/bridges/bin/rialto/runtime/src/millau_messages.rs b/bridges/bin/rialto/runtime/src/millau_messages.rs
index 1267cbd06e29..2de74f4c6b96 100644
--- a/bridges/bin/rialto/runtime/src/millau_messages.rs
+++ b/bridges/bin/rialto/runtime/src/millau_messages.rs
@@ -233,7 +233,7 @@ impl messages::BridgedChainWithMessages for Millau {
 	}
 }
 
-impl TargetHeaderChain<ToMillauMessagePayload, bp_millau::AccountId> for Millau {
+impl TargetHeaderChain<ToMillauMessagePayload, bp_rialto::AccountId> for Millau {
 	type Error = &'static str;
 	// The proof is:
 	// - hash of the header this proof has been created with;
diff --git a/bridges/primitives/messages/src/source_chain.rs b/bridges/primitives/messages/src/source_chain.rs
index c03d303ee841..5c6283a80360 100644
--- a/bridges/primitives/messages/src/source_chain.rs
+++ b/bridges/primitives/messages/src/source_chain.rs
@@ -61,6 +61,10 @@ pub struct RelayerRewards<Balance> {
 /// All implementations of this trait should only work with finalized data that
 /// can't change. Wrong implementation may lead to invalid lane states (i.e. lane
 /// that's stuck) and/or processing messages without paying fees.
+///
+/// The `Payload` type here means the payload of the message that is sent from the
+/// source chain to the target chain. The `AccountId` type here means the account
+/// type used by the source chain.
 pub trait TargetHeaderChain<Payload, AccountId> {
 	/// Error type.
 	type Error: Debug + Into<&'static str>;