diff --git a/node/cli/src/command.rs b/node/cli/src/command.rs
index 33c6a4b973..2d42997ad2 100644
--- a/node/cli/src/command.rs
+++ b/node/cli/src/command.rs
@@ -175,7 +175,6 @@ impl SubstrateCli for RelayChainCli {
 	}
 
 	fn load_spec(&self, id: &str) -> std::result::Result<Box<dyn sc_service::ChainSpec>, String> {
-		println!("Loading chain spec {}", id);
 		if id == "rococo-mandala" {
 			let spec = sc_service::GenericChainSpec::<(), polkadot_service::chain_spec::Extensions>::from_json_bytes(
 				&include_bytes!("../../../resources/rococo-mandala.json")[..],
diff --git a/node/service/src/chain_spec/acala.rs b/node/service/src/chain_spec/acala.rs
index 2fe351d40e..b8880c3395 100644
--- a/node/service/src/chain_spec/acala.rs
+++ b/node/service/src/chain_spec/acala.rs
@@ -170,6 +170,7 @@ pub fn latest_acala_config() -> Result<ChainSpec, String> {
 		Extensions {
 			relay_chain: "polkadot".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
@@ -207,6 +208,7 @@ pub fn acala_dev_config() -> Result<ChainSpec, String> {
 		Extensions {
 			relay_chain: "rococo-local".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
diff --git a/node/service/src/chain_spec/karura.rs b/node/service/src/chain_spec/karura.rs
index 36ee7ec29d..1d571533f5 100644
--- a/node/service/src/chain_spec/karura.rs
+++ b/node/service/src/chain_spec/karura.rs
@@ -90,6 +90,7 @@ pub fn karura_dev_config() -> Result<ChainSpec, String> {
 		Extensions {
 			relay_chain: "rococo-local".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
diff --git a/node/service/src/chain_spec/mandala.rs b/node/service/src/chain_spec/mandala.rs
index e9b348edda..3a21fadfd6 100644
--- a/node/service/src/chain_spec/mandala.rs
+++ b/node/service/src/chain_spec/mandala.rs
@@ -88,6 +88,7 @@ fn dev_testnet_config_from_chain_id(chain_id: &str) -> Result<ChainSpec, String>
 		Extensions {
 			relay_chain: "rococo-local".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
@@ -141,6 +142,7 @@ pub fn local_testnet_config() -> Result<ChainSpec, String> {
 		Extensions {
 			relay_chain: "rococo-local".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
@@ -221,6 +223,7 @@ pub fn latest_mandala_testnet_config() -> Result<ChainSpec, String> {
 		Extensions {
 			relay_chain: "dev".into(),
 			para_id: PARA_ID,
+			bad_blocks: None,
 		},
 	))
 }
diff --git a/node/service/src/chain_spec/mod.rs b/node/service/src/chain_spec/mod.rs
index cdbfa5efc0..9e076b0b07 100644
--- a/node/service/src/chain_spec/mod.rs
+++ b/node/service/src/chain_spec/mod.rs
@@ -51,6 +51,9 @@ pub struct Extensions {
 	pub relay_chain: String,
 	/// The id of the Parachain.
 	pub para_id: u32,
+	/// Known bad block hashes.
+	#[serde(default)]
+	pub bad_blocks: sc_client_api::BadBlocks<polkadot_primitives::v1::Block>,
 }
 
 impl Extensions {
diff --git a/resources/acala-dist.json b/resources/acala-dist.json
index 6efe7270ca..0362385bb1 100644
--- a/resources/acala-dist.json
+++ b/resources/acala-dist.json
@@ -31,6 +31,9 @@
   "paraId": 2000,
   "consensusEngine": null,
   "codeSubstitutes": {},
+  "badBlocks": [
+	"0xa820d0e6b3babb3a7023a229cfe61c32ceb68602f5339e2d416d7fbca5e82aa7"
+  ],
   "genesis": {
     "raw": {
       "top": {