diff --git a/src/config/config.js b/src/config/config.js
index a59218ea..9e53b925 100644
--- a/src/config/config.js
+++ b/src/config/config.js
@@ -183,5 +183,12 @@ export default {
    * @memberof module:config
    * @property {Integer} max_userid_length
    */
-  max_userid_length: 1024 * 5
+  max_userid_length: 1024 * 5,
+  /**
+   * Contains notatations that are considered "known". Known notations do not trigger
+   * validation error when the notation is marked as critical.
+   * @memberof module:config
+   * @property {Array} known_notations
+   */
+  known_notations: ["preferred-email-encoding@pgp.com", "pka-address@gnupg.org"]
 };
diff --git a/src/packet/signature.js b/src/packet/signature.js
index 2dc13719..5b01da2a 100644
--- a/src/packet/signature.js
+++ b/src/packet/signature.js
@@ -32,6 +32,7 @@ import type_mpi from '../type/mpi.js';
 import crypto from '../crypto';
 import enums from '../enums';
 import util from '../util';
+import config from '../config';
 
 /**
  * Implementation of the Signature Packet (Tag 2)
@@ -446,6 +447,10 @@ Signature.prototype.read_sub_packet = function (bytes, trusted=true) {
         const value = util.Uint8Array_to_str(bytes.subarray(mypos + m, mypos + m + n));
 
         this.notations.push([name, value]);
+
+        if (critical && (config.known_notations.indexOf(name) === -1)) {
+          throw new Error("Unknown critical notation: " + name);
+        }
       } else {
         util.print_debug("Unsupported notation flag "+bytes[mypos]);
       }
diff --git a/test/general/signature.js b/test/general/signature.js
index 9c4f2af7..e4f8163b 100644
--- a/test/general/signature.js
+++ b/test/general/signature.js
@@ -467,6 +467,16 @@ describe("Signature", function() {
         '=NbaL',
         '-----END PGP PRIVATE KEY BLOCK-----'].join("\n");
 
+  const signature_with_critical_notation = `-----BEGIN PGP MESSAGE-----
+
+owGbwMvMwMH4oOW7S46CznTG09xJDDE3Wl1KUotLuDousDAwcjBYiSmyXL+48d6x
+U1PSGUxcj8IUszKBVMpMaWAAAgEGZpAeh9SKxNyCnFS95PzcytRiBi5OAZjyXXzM
+f8WYLqv7TXP61Sa4rqT12CI3xaN73YS2pt089f96odCKaEPnWJ3iSGmzJaW/ug10
+2Zo8Wj2k4s7t8wt4H3HtTu+y5UZfV3VOO+l//sdE/o+Lsub8FZH7/eOq7OnbNp4n
+vwjE8mqJXetNMfj8r2SCyvkEnlVRYR+/mnge+ib56FdJ8uKtqSxyvgA=
+=fRXs
+-----END PGP MESSAGE-----`;
+
   it('Testing signature checking on CAST5-enciphered message', async function() {
     const priv_key = (await openpgp.key.readArmored(priv_key_arm1)).keys[0];
     const pub_key = (await openpgp.key.readArmored(pub_key_arm1)).keys[0];
@@ -606,6 +616,39 @@ describe("Signature", function() {
     });
   });
 
+  it('Verify fails with signed message with critical notations', async function() {
+    let testFailed = true;
+    try {
+      openpgp.config.tolerant = false;
+      const sMsg = await openpgp.message.readArmored(signature_with_critical_notation);
+      const pub_key = (await openpgp.key.readArmored(pub_key_arm2)).keys[0];
+      const verified = await sMsg.verify([pub_key]);
+      await verified[0].verified;
+      testFailed = false;
+    } catch (e) {
+      expect(e.message).to.equal('Unknown critical notation: test@example.com');
+    } finally {
+      openpgp.config.tolerant = true;
+    }
+    // fail the test if execution does not throw an exception
+    expect(testFailed).to.be.true;
+  });
+
+  it('Verify succeeds with known signed message with critical notations', async function() {
+    openpgp.config.tolerant = false;
+    openpgp.config.known_notations.push('test@example.com');
+    try {
+      const sMsg = await openpgp.message.readArmored(signature_with_critical_notation);
+      const pub_key = (await openpgp.key.readArmored(pub_key_arm2)).keys[0];
+      const verified = await sMsg.verify([pub_key]);
+      openpgp.stream.pipe(sMsg.getLiteralData(), new WritableStream());
+      expect(await verified[0].verified).to.be.true;
+    } finally {
+      openpgp.config.known_notations.pop();
+      openpgp.config.tolerant = true;
+    }
+  });
+
   it('Verify cleartext signed message with two signatures with openpgp.verify', async function() {
     const msg_armor =
       ['-----BEGIN PGP SIGNED MESSAGE-----',