diff --git a/src/key.js b/src/key.js
index 3fc308d0..8437520e 100644
--- a/src/key.js
+++ b/src/key.js
@@ -916,6 +916,10 @@ function generate(options) {
   if (options.keyType !== enums.publicKey.rsa_encrypt_sign) {
     throw new Error('Only RSA Encrypt or Sign supported');
   }
+  // Key without passphrase is unlocked by definition
+  if (!options.passphrase) {
+    options.unlocked = true;
+  }
 
   var packetlist = new packet.List();
 
diff --git a/src/packet/secret_key.js b/src/packet/secret_key.js
index be3cc5aa..8877b917 100644
--- a/src/packet/secret_key.js
+++ b/src/packet/secret_key.js
@@ -279,6 +279,9 @@ SecretKey.prototype.generate = function (bits) {
  * Clear private MPIs, return to initial state
  */
 SecretKey.prototype.clearPrivateMPIs = function () {
+  if (!this.encrypted) {
+    throw new Error('If secret key is not encrypted, clearing private MPIs is irreversible.');
+  }
   this.mpi = this.mpi.slice(0, crypto.getPublicMpiCount(this.algorithm));
   this.isDecrypted = false;
 };
diff --git a/test/general/signature.js b/test/general/signature.js
index 1da22c0e..e4b7ebeb 100644
--- a/test/general/signature.js
+++ b/test/general/signature.js
@@ -636,4 +636,13 @@ describe("Signature", function() {
     expect(result[0].valid).to.be.true;
   });
 
+  it('Sign message with key without password', function() {
+    var key = openpgp.generateKeyPair({numBits: 512, userId: 'ABC', passphrase: null}).key;
+
+    var message = openpgp.message.fromText('hello world');
+    message = message.sign([key]);
+
+    expect(message).to.exist;
+  });
+
 });