diff --git a/common/chain.go b/common/chain.go
index 0952a64b49..210a96d1f4 100644
--- a/common/chain.go
+++ b/common/chain.go
@@ -124,6 +124,16 @@ func IsEthereumChain(chainID int64) bool {
 		chainID == 1337 // eth privnet
 }
 
+func IsBscChain(chainID int64) bool {
+	return chainID == 56 || // bsc mainnet
+		chainID == 97 // BSC testnet
+}
+
+func IsPolygonChain(chainID int64) bool {
+	return chainID == 137 || // polygon mainnet
+		chainID == 80001 // polygon mumbai
+}
+
 // IsEmpty is to determinate whether the chain is empty
 func (chain Chain) IsEmpty() bool {
 	return strings.TrimSpace(chain.String()) == ""
diff --git a/zetaclient/evm_client.go b/zetaclient/evm_client.go
index ad79f68d77..311b800aef 100644
--- a/zetaclient/evm_client.go
+++ b/zetaclient/evm_client.go
@@ -847,7 +847,7 @@ func (ob *EVMChainClient) observeInTX() error {
 					continue
 				}
 
-				if ob.chain.ChainId != common.MumbaiChain().ChainId {
+				if !common.IsPolygonChain(ob.chain.ChainId) {
 					_, ballotIdentifier, err := ob.zetaClient.PostAddBlockHeader(
 						ob.chain.ChainId,
 						block.Hash().Bytes(),