diff --git a/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.test.ts b/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.test.ts
index 818eca25e..9ad5427da 100644
--- a/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.test.ts
+++ b/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.test.ts
@@ -169,16 +169,18 @@ describe('BitcoinChainAdapter', () => {
     it('should throw if called with invalid chainId', () => {
       args.chainId = 'INVALID_CHAINID'
       expect(() => new bitcoin.ChainAdapter(args)).toThrow(
-        /fromCAIP19: error parsing caip19, chain: (.+), network: undefined/
+        'Bitcoin chainId INVALID_CHAINID not supported'
       )
     })
     it('should throw if called with non bitcoin chainId', () => {
       args.chainId = 'eip155:1'
-      expect(() => new bitcoin.ChainAdapter(args)).toThrow(/chainId must be a bitcoin chain type/)
+      expect(() => new bitcoin.ChainAdapter(args)).toThrow('Bitcoin chainId eip155:1 not supported')
     })
-    it('should throw if called with no chainId', () => {
+    it('should use default chainId if no arg chainId provided.', () => {
       args.chainId = undefined
-      expect(() => new bitcoin.ChainAdapter(args)).toThrow(/chainId required/)
+      const adapter = new bitcoin.ChainAdapter(args)
+      const chainId = adapter.getChainId()
+      expect(chainId).toEqual('bip122:000000000019d6689c085ae165831e93')
     })
   })
 
diff --git a/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.ts b/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.ts
index 2e037ec8e..1f128aff9 100644
--- a/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.ts
+++ b/packages/chain-adapters/src/bitcoin/BitcoinChainAdapter.ts
@@ -1,4 +1,4 @@
-import { AssetNamespace, AssetReference, caip2, caip19 } from '@shapeshiftoss/caip'
+import { AssetNamespace, AssetReference, CAIP2, caip2, caip19 } from '@shapeshiftoss/caip'
 import {
   bip32ToAddressNList,
   BTCOutputAddressType,
@@ -33,17 +33,25 @@ export class ChainAdapter
     coinType: 0,
     accountNumber: 0
   }
+  protected readonly supportedChainIds: CAIP2[] = [
+    'bip122:000000000019d6689c085ae165831e93',
+    'bip122:000000000933ea01ad0ee984209779ba'
+  ]
+  chainId = this.supportedChainIds[0]
 
   constructor(args: ChainAdapterArgs) {
     super(args)
-    if (!args.chainId) {
-      throw new Error('chainId required')
+    if (args.chainId && !this.supportedChainIds.includes(args.chainId))
+      throw new Error(`Bitcoin chainId ${args.chainId} not supported`)
+    if (args.chainId) {
+      this.chainId = args.chainId
+    } else {
+      this.chainId = this.supportedChainIds[0]
     }
-    const { chain, network } = caip2.fromCAIP2(args.chainId)
+    const { chain, network } = caip2.fromCAIP2(this.chainId)
     if (chain !== ChainTypes.Bitcoin) {
       throw new Error('chainId must be a bitcoin chain type')
     }
-    this.chainId = args.chainId
     this.coinName = args.coinName
     this.assetId = caip19.toCAIP19({
       chain,
diff --git a/packages/chain-adapters/src/utxo/UTXOBaseAdapter.ts b/packages/chain-adapters/src/utxo/UTXOBaseAdapter.ts
index a9ed3c9d1..354b57014 100644
--- a/packages/chain-adapters/src/utxo/UTXOBaseAdapter.ts
+++ b/packages/chain-adapters/src/utxo/UTXOBaseAdapter.ts
@@ -39,6 +39,7 @@ export abstract class UTXOBaseAdapter<T extends UTXOChainTypes> implements IChai
   protected chainId: CAIP2
   protected assetId: CAIP19
   protected coinName: string
+  protected readonly supportedChainIds: CAIP2[]
   protected readonly providers: {
     http: unchained.bitcoin.V1Api
     ws: unchained.ws.Client<unchained.SequencedTx>