diff --git a/packages/cashscript/src/Argument.ts b/packages/cashscript/src/Argument.ts
index 915fe84d..5913e82f 100644
--- a/packages/cashscript/src/Argument.ts
+++ b/packages/cashscript/src/Argument.ts
@@ -59,16 +59,20 @@ export function encodeFunctionArgument(argument: FunctionArgument, typeStr: stri
     throw Error(`Value for type ${type} should be a Uint8Array or hex string`);
   }
 
-  // Redefine SIG as a bytes65 so it is included in the size checks below
-  // Note that ONLY Schnorr signatures are accepted
+  // Redefine SIG as a bytes65 (Schnorr) or bytes71, bytes72 (ECDSA)
   if (type === PrimitiveType.SIG && argument.byteLength !== 0) {
-    type = new BytesType(65);
+    if (![65, 71, 72].includes(argument.byteLength)) {
+      throw new TypeError(`bytes${argument.byteLength}`, type);
+    }
+    type = new BytesType(argument.byteLength);
   }
 
-  // Redefine DATASIG as a bytes64 so it is included in the size checks below
-  // Note that ONLY Schnorr signatures are accepted
+  // Redefine DATASIG as a bytes64 (Schnorr) or bytes70 (ECDSA) so it is included in the size checks below
   if (type === PrimitiveType.DATASIG && argument.byteLength !== 0) {
-    type = new BytesType(64);
+    if (![64, 70].includes(argument.byteLength)) {
+      throw new TypeError(`bytes${argument.byteLength}`, type);
+    }
+    type = new BytesType(argument.byteLength);
   }
 
   // Bounded bytes types require a correctly sized argument
diff --git a/packages/cashscript/test/e2e/HodlVault.test.ts b/packages/cashscript/test/e2e/HodlVault.test.ts
index f9ef0a92..af88689c 100644
--- a/packages/cashscript/test/e2e/HodlVault.test.ts
+++ b/packages/cashscript/test/e2e/HodlVault.test.ts
@@ -5,6 +5,8 @@ import {
   ElectrumNetworkProvider,
   Network,
   TransactionBuilder,
+  SignatureAlgorithm,
+  HashType,
 } from '../../src/index.js';
 import {
   alicePriv,
@@ -16,6 +18,7 @@ import { gatherUtxos, getTxOutputs } from '../test-util.js';
 import { FailedRequireError } from '../../src/Errors.js';
 import artifact from '../fixture/hodl_vault.artifact.js';
 import { randomUtxo } from '../../src/utils.js';
+import { placeholder } from '@cashscript/utils';
 
 describe('HodlVault', () => {
   const provider = process.env.TESTS_USE_MOCKNET
@@ -94,5 +97,52 @@ describe('HodlVault', () => {
       const txOutputs = getTxOutputs(tx);
       expect(txOutputs).toEqual(expect.arrayContaining([{ to, amount }]));
     });
+
+    it('should succeed when price is high enough, ECDSA sig and datasig', async () => {
+      // given
+      const message = oracle.createMessage(100000n, 30000n);
+      const oracleSig = oracle.signMessage(message, SignatureAlgorithm.ECDSA);
+      const to = hodlVault.address;
+      const amount = 10000n;
+      const { utxos, changeAmount } = gatherUtxos(await hodlVault.getUtxos(), { amount, fee: 2000n });
+
+      const signatureTemplate = new SignatureTemplate(alicePriv, HashType.SIGHASH_ALL, SignatureAlgorithm.ECDSA);
+
+      // when
+      const tx = await new TransactionBuilder({ provider })
+        .addInputs(utxos, hodlVault.unlock.spend(signatureTemplate, oracleSig, message))
+        .addOutput({ to: to, amount: amount })
+        .addOutput({ to: to, amount: changeAmount })
+        .setLocktime(100_000)
+        .send();
+
+      // then
+      const txOutputs = getTxOutputs(tx);
+      expect(txOutputs).toEqual(expect.arrayContaining([{ to, amount }]));
+    });
+
+    it('should fail to accept wrong signature lengths', async () => {
+      // given
+      const message = oracle.createMessage(100000n, 30000n);
+      const oracleSig = oracle.signMessage(message, SignatureAlgorithm.ECDSA);
+      const to = hodlVault.address;
+      const amount = 10000n;
+      const { utxos, changeAmount } = gatherUtxos(await hodlVault.getUtxos(), { amount, fee: 2000n });
+
+      expect(() => new TransactionBuilder({ provider })
+        .addInputs(utxos, hodlVault.unlock.spend(placeholder(100), oracleSig, message))
+        .addOutput({ to: to, amount: amount })
+        .addOutput({ to: to, amount: changeAmount })
+        .setLocktime(100_000)
+        .send()).toThrow("Found type 'bytes100' where type 'sig' was expected");
+
+      const signatureTemplate = new SignatureTemplate(alicePriv, HashType.SIGHASH_ALL, SignatureAlgorithm.ECDSA);
+      expect(() => new TransactionBuilder({ provider })
+        .addInputs(utxos, hodlVault.unlock.spend(signatureTemplate, placeholder(100), message))
+        .addOutput({ to: to, amount: amount })
+        .addOutput({ to: to, amount: changeAmount })
+        .setLocktime(100_000)
+        .send()).toThrow("Found type 'bytes100' where type 'datasig' was expected");
+    });
   });
 });
diff --git a/packages/cashscript/test/fixture/PriceOracle.ts b/packages/cashscript/test/fixture/PriceOracle.ts
index eb174099..f8643ac4 100644
--- a/packages/cashscript/test/fixture/PriceOracle.ts
+++ b/packages/cashscript/test/fixture/PriceOracle.ts
@@ -1,5 +1,6 @@
 import { padMinimallyEncodedVmNumber, flattenBinArray, secp256k1 } from '@bitauth/libauth';
 import { encodeInt, sha256 } from '@cashscript/utils';
+import { SignatureAlgorithm } from '../../src/index.js';
 
 export class PriceOracle {
   constructor(public privateKey: Uint8Array) {}
@@ -12,8 +13,11 @@ export class PriceOracle {
     return flattenBinArray([encodedBlockHeight, encodedBchUsdPrice]);
   }
 
-  signMessage(message: Uint8Array): Uint8Array {
-    const signature = secp256k1.signMessageHashSchnorr(this.privateKey, sha256(message));
+  signMessage(message: Uint8Array, signatureAlgorithm: SignatureAlgorithm = SignatureAlgorithm.SCHNORR): Uint8Array {
+    const signature = signatureAlgorithm === SignatureAlgorithm.SCHNORR ?
+      secp256k1.signMessageHashSchnorr(this.privateKey, sha256(message)) :
+      secp256k1.signMessageHashDER(this.privateKey, sha256(message));
+
     if (typeof signature === 'string') throw new Error();
     return signature;
   }