diff --git a/src/cleartext.js b/src/cleartext.js
index 84252017..a3ce9895 100644
--- a/src/cleartext.js
+++ b/src/cleartext.js
@@ -29,7 +29,7 @@ import armor from './encoding/armor';
 import enums from './enums';
 import packet from './packet';
 import { Signature } from './signature';
-import { createVerificationObjects } from './message';
+import { createVerificationObjects, createSignaturePackets } from './message';
 import { getPreferredHashAlgo } from './key';
 
 /**
@@ -80,34 +80,10 @@ CleartextMessage.prototype.sign = async function(privateKeys) {
  * @return {module:signature~Signature}      new detached signature of message content
  */
 CleartextMessage.prototype.signDetached = async function(privateKeys) {
-  const packetlist = new packet.List();
   const literalDataPacket = new packet.Literal();
   literalDataPacket.setText(this.text);
 
-  await Promise.all(privateKeys.map(async function(privateKey) {
-    if (privateKey.isPublic()) {
-      throw new Error('Need private key for signing');
-    }
-    await privateKey.verifyPrimaryUser();
-    const signingKeyPacket = privateKey.getSigningKeyPacket();
-    if (!signingKeyPacket) {
-      throw new Error('Could not find valid key packet for signing in key ' +
-                      privateKey.primaryKey.getKeyId().toHex());
-    }
-    const signaturePacket = new packet.Signature();
-    signaturePacket.signatureType = enums.signature.text;
-    signaturePacket.publicKeyAlgorithm = signingKeyPacket.algorithm;
-    signaturePacket.hashAlgorithm = getPreferredHashAlgo(privateKey);
-    if (!signingKeyPacket.isDecrypted) {
-      throw new Error('Private key is not decrypted.');
-    }
-    await signaturePacket.sign(signingKeyPacket, literalDataPacket);
-    return signaturePacket;
-  })).then(signatureList => {
-    signatureList.forEach(signaturePacket => packetlist.push(signaturePacket));
-  });
-
-  return new Signature(packetlist);
+  return new Signature(await createSignaturePackets(literalDataPacket, privateKeys));
 };
 
 /**
diff --git a/src/message.js b/src/message.js
index 1fc0c96c..01838921 100644
--- a/src/message.js
+++ b/src/message.js
@@ -416,25 +416,7 @@ Message.prototype.sign = async function(privateKeys=[], signature=null) {
   });
 
   packetlist.push(literalDataPacket);
-
-  await Promise.all(privateKeys.map(async function(privateKey) {
-    const signaturePacket = new packet.Signature();
-    const signingKeyPacket = privateKey.getSigningKeyPacket();
-    if (!signingKeyPacket.isDecrypted) {
-      throw new Error('Private key is not decrypted.');
-    }
-    signaturePacket.signatureType = signatureType;
-    signaturePacket.hashAlgorithm = getPreferredHashAlgo(privateKey);
-    signaturePacket.publicKeyAlgorithm = signingKeyPacket.algorithm;
-    await signaturePacket.sign(signingKeyPacket, literalDataPacket);
-    return signaturePacket;
-  })).then(signatureList => {
-    signatureList.forEach(signaturePacket => packetlist.push(signaturePacket));
-  });
-
-  if (signature) {
-    packetlist.concat(existingSigPacketlist);
-  }
+  packetlist.concat(await createSignaturePackets(literalDataPacket, privateKeys, signature));
 
   return new Message(packetlist);
 };
@@ -466,24 +448,40 @@ Message.prototype.compress = function(compression) {
  * @return {module:signature~Signature}      new detached signature of message content
  */
 Message.prototype.signDetached = async function(privateKeys=[], signature=null) {
-  const packetlist = new packet.List();
-
   const literalDataPacket = this.packets.findPacket(enums.packet.literal);
   if (!literalDataPacket) {
     throw new Error('No literal data packet to sign.');
   }
+  return new Signature(await createSignaturePackets(literalDataPacket, privateKeys, signature));
+};
+
+/**
+ * Create signature packets for the message
+ * @param  {module:packet/literal}           the literal data packet to sign
+ * @param  {Array<module:key~Key>}           privateKey private keys with decrypted secret key data for signing
+ * @param  {Signature} signature             (optional) any existing detached signature to append
+ * @return {module:packet/packetlist}        list of signature packets
+ */
+export async function createSignaturePackets(literalDataPacket, privateKeys, signature=null) {
+  const packetlist = new packet.List();
 
   const literalFormat = enums.write(enums.literal, literalDataPacket.format);
   const signatureType = literalFormat === enums.literal.binary ?
     enums.signature.binary : enums.signature.text;
 
   await Promise.all(privateKeys.map(async function(privateKey) {
-    const signaturePacket = new packet.Signature();
+    if (privateKey.isPublic()) {
+      throw new Error('Need private key for signing');
+    }
     await privateKey.verifyPrimaryUser();
     const signingKeyPacket = privateKey.getSigningKeyPacket();
+    if (!signingKeyPacket) {
+      throw new Error('Could not find valid key packet for signing in key ' + privateKey.primaryKey.getKeyId().toHex());
+    }
     if (!signingKeyPacket.isDecrypted) {
       throw new Error('Private key is not decrypted.');
     }
+    const signaturePacket = new packet.Signature();
     signaturePacket.signatureType = signatureType;
     signaturePacket.publicKeyAlgorithm = signingKeyPacket.algorithm;
     signaturePacket.hashAlgorithm = getPreferredHashAlgo(privateKey);
@@ -497,10 +495,8 @@ Message.prototype.signDetached = async function(privateKeys=[], signature=null)
     const existingSigPacketlist = signature.packets.filterByTag(enums.packet.signature);
     packetlist.concat(existingSigPacketlist);
   }
-
-  return new Signature(packetlist);
-};
-
+  return packetlist;
+}
 
 /**
  * Verify message signatures
diff --git a/test/general/openpgp.js b/test/general/openpgp.js
index 476f0c11..e45f6c01 100644
--- a/test/general/openpgp.js
+++ b/test/general/openpgp.js
@@ -1279,7 +1279,7 @@ describe('OpenPGP.js public api tests', function() {
               privateKeys: [privateKey.keys[0], privKeyDE]
             };
             const verifyOpt = {
-              publicKeys: publicKey.keys
+              publicKeys: [publicKey.keys[0], privKeyDE.toPublic()]
             };
             return openpgp.sign(signOpt).then(function (signed) {
               expect(signed.data).to.match(/-----BEGIN PGP SIGNED MESSAGE-----/);
@@ -1290,6 +1290,9 @@ describe('OpenPGP.js public api tests', function() {
               expect(verified.signatures[0].valid).to.be.true;
               expect(verified.signatures[0].keyid.toHex()).to.equal(privateKey.keys[0].getSigningKeyPacket().getKeyId().toHex());
               expect(verified.signatures[0].signature.packets.length).to.equal(1);
+              expect(verified.signatures[1].valid).to.be.true;
+              expect(verified.signatures[1].keyid.toHex()).to.equal(privKeyDE.getSigningKeyPacket().getKeyId().toHex());
+              expect(verified.signatures[1].signature.packets.length).to.equal(1);
             });
           });