diff --git a/add-on/src/lib/ipfs-proxy/pre-acl.js b/add-on/src/lib/ipfs-proxy/pre-acl.js
index 990a0e4a8..3061d1285 100644
--- a/add-on/src/lib/ipfs-proxy/pre-acl.js
+++ b/add-on/src/lib/ipfs-proxy/pre-acl.js
@@ -21,7 +21,11 @@ function createPreAcl (permission, getState, getScope, accessControl, requestAcc
       access = await accessControl.setAccess(scope, wildcard ? '*' : permission, allow)
     }
 
-    if (!access.allow) throw new Error(`User denied access to ${permission}`)
+    if (!access.allow) {
+      const err = new Error(`User denied access to ${permission}`)
+      err.output = { payload: { isIpfsProxyAclError: true, permission, scope } }
+      throw err
+    }
 
     return args
   }
diff --git a/add-on/src/lib/ipfs-proxy/pre-mfs-scope.js b/add-on/src/lib/ipfs-proxy/pre-mfs-scope.js
index f8af1e341..e04315c20 100644
--- a/add-on/src/lib/ipfs-proxy/pre-mfs-scope.js
+++ b/add-on/src/lib/ipfs-proxy/pre-mfs-scope.js
@@ -1,4 +1,5 @@
-const Path = require('path')
+// Use path-browserify for consistent behavior between browser and tests on Windows
+const Path = require('path-browserify')
 const DEFAULT_ROOT_PATH = '/dapps'
 
 // Creates a "pre" function that is called prior to calling a real function
diff --git a/add-on/src/lib/ipfs-proxy/request-access.js b/add-on/src/lib/ipfs-proxy/request-access.js
index 5f3a99667..d9f2b0e74 100644
--- a/add-on/src/lib/ipfs-proxy/request-access.js
+++ b/add-on/src/lib/ipfs-proxy/request-access.js
@@ -98,7 +98,9 @@ function createRequestAccess (browser, screen) {
     const userTabRemoved = new Promise((resolve, reject) => {
       onTabRemoved = (id) => {
         if (id !== tabId) return
-        reject(new Error(`Failed to obtain access response for ${permission} at ${scope}`))
+        const err = new Error(`Failed to obtain access response for ${permission} at ${scope}`)
+        err.output = { payload: { isIpfsProxyAclError: true, scope, permission } }
+        reject(err)
       }
       browser.tabs.onRemoved.addListener(onTabRemoved)
     })
diff --git a/docs/window.ipfs.md b/docs/window.ipfs.md
index 767b5697b..cc4efd0be 100644
--- a/docs/window.ipfs.md
+++ b/docs/window.ipfs.md
@@ -38,19 +38,19 @@ if (window.ipfs) {
 To add and get content, you could do something like this:
 
 ```js
-if (window.ipfs) {  
+if (window.ipfs) {
   try {
-    await ipfs.add(Buffer.from('=^.^='))
-   } catch (err) {
-     if (err.message === 'User denied access to ipfs.files.add') {
-       // Fallback
-     } else {
-       throw err
-     }
-   }
-
-   const data = await ipfs.cat('QmS5RzFV9v4fucVtjATPxoxABgEmNhhduykzUbQeGyyS3N')
-   console.log(data.toString()) // =^.^=
+    const [{ hash }] = await ipfs.add(Buffer.from('=^.^='))
+    const data = await ipfs.cat(hash)
+    console.log(data.toString()) // =^.^=
+  } catch (err) {
+    if (err.isIpfsProxyAclError) {
+      // Fallback
+      console.log('Unable to get ACL decision from user :(', err)
+    } else {
+      throw err
+    }
+  }
 } else {
   // Fallback
 }
diff --git a/package.json b/package.json
index 115eea6ab..36bd49c76 100644
--- a/package.json
+++ b/package.json
@@ -44,7 +44,7 @@
     "watch:content-scripts:ipfs-proxy:page": "watchify -p prundupify -t [ browserify-package-json --global ] add-on/src/contentScripts/ipfs-proxy/page.js -o add-on/dist/contentScripts/ipfs-proxy/page.js -v",
     "watch:content-scripts:ipfs-proxy:content": "nodemon --exec \"browserify -p prundupify -t brfs -t [ browserify-package-json --global ] -s IpfsProxyContent add-on/src/contentScripts/ipfs-proxy/content.js -o add-on/dist/contentScripts/ipfs-proxy/content.js -v\" --watch add-on/src/contentScripts/ipfs-proxy/content.js --watch add-on/dist/contentScripts/ipfs-proxy/page.js",
     "test": "run-s test:*",
-    "test:functional": " nyc --reporter=lcov --reporter=text mocha --timeout 15000 --require ignore-styles --reporter mocha-jenkins-reporter 'test/functional/**/*.test.js'",
+    "test:functional": " nyc --reporter=lcov --reporter=text mocha --timeout 15000 --require ignore-styles --reporter mocha-jenkins-reporter \"test/functional/**/*.test.js\"",
     "lint": "run-s lint:*",
     "lint:standard": "standard -v \"add-on/src/**/*.js\" \"test/**/*.js\"",
     "lint:web-ext": "web-ext lint",
@@ -101,6 +101,7 @@
     "lru_map": "0.3.3",
     "mime-types": "2.1.18",
     "p-queue": "2.4.0",
+    "path-browserify": "0.0.0",
     "piggybacker": "2.0.0",
     "prundupify": "1.0.0",
     "tachyons": "4.9.1",
diff --git a/test/functional/lib/ipfs-proxy/pre-acl.test.js b/test/functional/lib/ipfs-proxy/pre-acl.test.js
index 1a9ee00d8..faba83f0c 100644
--- a/test/functional/lib/ipfs-proxy/pre-acl.test.js
+++ b/test/functional/lib/ipfs-proxy/pre-acl.test.js
@@ -117,6 +117,29 @@ describe('lib/ipfs-proxy/pre-acl', () => {
     expect(() => { if (error) throw error }).to.throw(`User denied access to ${permission}`)
   })
 
+  it('should have a well-formed Error if denied', async () => {
+    const getState = () => ({ ipfsProxy: true })
+    const accessControl = new AccessControl(new Storage())
+    const getScope = () => 'https://ipfs.io/'
+    const permission = 'files.add'
+    const requestAccess = Sinon.spy(async () => ({ allow: false }))
+    const preAcl = createPreAcl(permission, getState, getScope, accessControl, requestAccess)
+
+    let error
+
+    try {
+      await preAcl()
+    } catch (err) {
+      error = err
+    }
+
+    expect(error.output.payload).to.deep.eql({
+      isIpfsProxyAclError: true,
+      permission,
+      scope: getScope()
+    })
+  })
+
   it('should not re-request if allowed', async () => {
     const getState = () => ({ ipfsProxy: true })
     const accessControl = new AccessControl(new Storage())
diff --git a/yarn.lock b/yarn.lock
index 0c3f7278f..43ec641ca 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7176,7 +7176,7 @@ pascalcase@^0.1.1:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/pascalcase/-/pascalcase-0.1.1.tgz#b363e55e8006ca6fe21784d2db22bd15d7917f14"
 
-path-browserify@~0.0.0:
+path-browserify@0.0.0, path-browserify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/path-browserify/-/path-browserify-0.0.0.tgz#a0b870729aae214005b7d5032ec2cbbb0fb4451a"