diff --git a/src/key.js b/src/key.js
index 9bf95f89..195e9ec5 100644
--- a/src/key.js
+++ b/src/key.js
@@ -327,17 +327,17 @@ Key.prototype.getPreferredHashAlgorithm = function() {
 function isValidEncryptionKeyPacket(keyPacket, signature) {
   return keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.dsa) &&
          keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.rsa_sign) &&
-         ((signature.keyFlags & enums.keyFlags.encrypt_communication) !== 0 ||
-          (signature.keyFlags & enums.keyFlags.encrypt_storage) !== 0 ||
-          !signature.keyFlags);
+         (!signature.keyFlags ||
+          (signature.keyFlags[0] & enums.keyFlags.encrypt_communication) !== 0 ||
+          (signature.keyFlags[0] & enums.keyFlags.encrypt_storage) !== 0);
 }
 
 function isValidSigningKeyPacket(keyPacket, signature) {
   return (keyPacket.algorithm == enums.read(enums.publicKey, enums.publicKey.dsa) ||
           keyPacket.algorithm == enums.read(enums.publicKey, enums.publicKey.rsa_sign) ||
           keyPacket.algorithm == enums.read(enums.publicKey, enums.publicKey.rsa_encrypt_sign)) &&
-         ((signature.keyFlags & enums.keyFlags.sign_data) !== 0 ||
-          !signature.keyFlags);
+         (!signature.keyFlags ||
+          (signature.keyFlags[0] & enums.keyFlags.sign_data) !== 0);
 }
 
 /**
diff --git a/test/general/key.js b/test/general/key.js
index 75657025..377c9575 100644
--- a/test/general/key.js
+++ b/test/general/key.js
@@ -293,5 +293,20 @@ describe('Key', function() {
     expect(status).to.equal(openpgp.enums.keyStatus.revoked);
     done();
   });
+
+  it('Evaluate key flags to find valid encryption key packet', function() {
+    var pubKeys = openpgp.key.readArmored(pub_sig_test);
+    expect(pubKeys).to.exist;
+    expect(pubKeys.err).to.not.exist;
+    expect(pubKeys.keys).to.have.length(1);
+
+    var pubKey = pubKeys.keys[0];
+    // remove subkeys
+    pubKey.subKeys = null;
+    // primary key has only key flags for signing
+    var keyPacket = pubKey.getEncryptionKeyPacket();
+    expect(keyPacket).to.not.exist;
+  });
+
 });