diff --git a/README.md b/README.md
index 6b8660bdfd..f79cd8c23a 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@ OpenPGP.js [![BrowserStack Status](https://automate.browserstack.com/badge.svg?b
     - [Performance](#performance)
     - [Getting started](#getting-started)
         - [Node.js](#nodejs)
+        - [Deno (experimental)](#deno-experimental)
         - [Browser (webpack)](#browser-webpack)
         - [Browser (plain files)](#browser-plain-files)
     - [Examples](#examples)
@@ -109,6 +110,14 @@ Or as an ES6 module, from an .mjs file:
 import * as openpgp from 'openpgp';
 ```
 
+#### Deno (experimental)
+
+Import as an ES6 module, from an .mjs file on a CDN of your choice.
+
+```js
+import * as openpgp from "https://cdn.jsdelivr.net/npm/openpgp@5/dist/openpgp.mjs";
+```
+
 #### Browser (webpack)
 
 Install OpenPGP.js using npm and save it in your devDependencies:
diff --git a/src/crypto/hash/index.js b/src/crypto/hash/index.js
index cfec8d381e..8537b68505 100644
--- a/src/crypto/hash/index.js
+++ b/src/crypto/hash/index.js
@@ -75,9 +75,14 @@ if (nodeCrypto) { // Use Node native crypto for all hash functions
     ripemd: nodeHash('ripemd160')
   };
 } else { // Use JS fallbacks
+  let webCryptoHash = false,
+      hasUserAgentCaps = navigator && navigator.userAgent;
+  if (hasUserAgentCaps && navigator.userAgent.indexOf('Edge') === -1) {
+    webCryptoHash = 'SHA-1';
+  }
   hashFunctions = {
     md5: md5,
-    sha1: asmcryptoHash(Sha1, navigator.userAgent.indexOf('Edge') === -1 && 'SHA-1'),
+    sha1: asmcryptoHash(Sha1, webCryptoHash),
     sha224: hashjsHash(sha224),
     sha256: asmcryptoHash(Sha256, 'SHA-256'),
     sha384: hashjsHash(sha384, 'SHA-384'),
diff --git a/src/crypto/mode/eax.js b/src/crypto/mode/eax.js
index cf68c4600e..c0f53fdd94 100644
--- a/src/crypto/mode/eax.js
+++ b/src/crypto/mode/eax.js
@@ -48,10 +48,13 @@ async function OMAC(key) {
 }
 
 async function CTR(key) {
+  let 
+    hasUserAgentCaps = navigator && navigator.userAgent,
+    isEdge = hasUserAgentCaps && navigator.userAgent.indexOf('Edge') !== -1;
   if (
     util.getWebCrypto() &&
     key.length !== 24 && // WebCrypto (no 192 bit support) see: https://www.chromium.org/blink/webcrypto#TOC-AES-support
-    navigator.userAgent.indexOf('Edge') === -1
+    (!isEdge)
   ) {
     key = await webCrypto.importKey('raw', key, { name: 'AES-CTR', length: key.length * 8 }, false, ['encrypt']);
     return async function(pt, iv) {
diff --git a/src/crypto/mode/gcm.js b/src/crypto/mode/gcm.js
index 424b7e1afb..a310d2c850 100644
--- a/src/crypto/mode/gcm.js
+++ b/src/crypto/mode/gcm.js
@@ -52,11 +52,14 @@ async function GCM(cipher, key) {
 
     return {
       encrypt: async function(pt, iv, adata = new Uint8Array()) {
+        let 
+          hasUserAgentCaps = navigator && navigator.userAgent,
+          isEdge = hasUserAgentCaps && navigator.userAgent.indexOf('Edge') !== -1;
         if (
           !pt.length ||
           // iOS does not support GCM-en/decrypting empty messages
           // Also, synchronous en/decryption might be faster in this case.
-          (!adata.length && navigator.userAgent.indexOf('Edge') !== -1)
+          (!adata.length && isEdge)
           // Edge does not support GCM-en/decrypting without ADATA
         ) {
           return AES_GCM.encrypt(pt, key, iv, adata);
@@ -66,11 +69,14 @@ async function GCM(cipher, key) {
       },
 
       decrypt: async function(ct, iv, adata = new Uint8Array()) {
+        let 
+          hasUserAgentCaps = navigator && navigator.userAgent,
+          isEdge = hasUserAgentCaps && navigator.userAgent.indexOf('Edge') !== -1;
         if (
           ct.length === tagLength ||
           // iOS does not support GCM-en/decrypting empty messages
           // Also, synchronous en/decryption might be faster in this case.
-          (!adata.length && navigator.userAgent.indexOf('Edge') !== -1)
+          (!adata.length && isEdge)
           // Edge does not support GCM-en/decrypting without ADATA
         ) {
           return AES_GCM.decrypt(ct, key, iv, adata);
diff --git a/src/util.js b/src/util.js
index a510bc3945..b49fd9bb6e 100644
--- a/src/util.js
+++ b/src/util.js
@@ -429,8 +429,11 @@ const util = {
       const os = require('os');
       return os.cpus().length;
     }
-
-    return navigator.hardwareConcurrency || 1;
+    if (navigator && navigator.hardwareConcurrency) {
+      return navigator.hardwareConcurrency || 1;
+    } else {
+      return 1;
+    }
   },
 
   isEmailAddress: function(data) {
diff --git a/test/general/streaming.js b/test/general/streaming.js
index 6839f1f4ff..62327ca9ff 100644
--- a/test/general/streaming.js
+++ b/test/general/streaming.js
@@ -918,7 +918,9 @@ function tests() {
         if (util.detectNode()) {
           coresStub.restore();
         } else {
-          delete navigator.hardwareConcurrency;
+          if (navigator && navigator.hardwareConcurrency !== void 0) {
+            delete navigator.hardwareConcurrency;
+          }
         }
       }
     });
diff --git a/test/worker/application_worker.js b/test/worker/application_worker.js
index f40dd9f559..1de0396425 100644
--- a/test/worker/application_worker.js
+++ b/test/worker/application_worker.js
@@ -12,7 +12,7 @@ module.exports = () => tryTests('Application Worker', tests, {
 function tests() {
 
   it('Should support loading OpenPGP.js from inside a Web Worker', async function() {
-    if (/Edge/.test(navigator.userAgent)) {
+    if (navigator && navigator.userAgent && /Edge/.test(navigator.userAgent)) {
       this.skip(); // Old Edge doesn't support crypto.getRandomValues inside a Worker.
     }
     try {