diff --git a/atom/browser/api/atom_api_app.cc b/atom/browser/api/atom_api_app.cc
index 47ce814c6ec1..904a63a5d09f 100644
--- a/atom/browser/api/atom_api_app.cc
+++ b/atom/browser/api/atom_api_app.cc
@@ -886,7 +886,7 @@ void App::GetFileIcon(const base::FilePath& path,
   }
 
   if (!args->GetNext(&callback)) {
-    args->ThrowError();
+    args->ThrowError("Missing required callback function");
     return;
   }
 
diff --git a/docs/api/app.md b/docs/api/app.md
index 5bd12f361d61..e825add47e89 100644
--- a/docs/api/app.md
+++ b/docs/api/app.md
@@ -405,11 +405,17 @@ You can request the following paths by the name:
 
 * `path` String
 * `options` Object (optional)
-  * `size` String - Can be `small`, `normal`, `large`. Except for `large` on _macOS_
+  * `size` String - Can be `small`, `normal`, `large`. The `large` size is not supported on _macOS_
 * `callback` Function
   * `error` `Error`
   * `icon` [NativeImage](native-image.md)
 
+Fetches associated icon for using OS rules for handling icons.
+On _Windows_, there a 2 kinds of icons:
+- icons associated with certain file extension - `.mp3`, `.png`, etc.
+- icons inside file itself, like `.exe`, `.dll`, `.ico`.
+On _Linux_ and _macOS_, icons depend on application associated with file mime type.
+
 ### `app.setPath(name, path)`
 
 * `name` String
diff --git a/spec/api-app-spec.js b/spec/api-app-spec.js
index 2508efe388fa..f158cc851a01 100644
--- a/spec/api-app-spec.js
+++ b/spec/api-app-spec.js
@@ -458,7 +458,7 @@ describe('app module', function () {
   })
 
   describe('getFileIcon() API', function () {
-    const iconPath = path.join(process.cwd(), 'fixtures/assets/icon.ico')
+    const iconPath = path.join(__dirname, 'fixtures/assets/icon.ico')
     const sizes = {
       small: 16,
       normal: 32,
@@ -484,7 +484,7 @@ describe('app module', function () {
     })
 
     describe('size option', function () {
-      it('fetches small icons', function (done) {
+      it('fetches small icon', function (done) {
         app.getFileIcon(iconPath, { size: 'small' }, function (err, icon) {
           const size = icon.getSize()
           assert.equal(err, null)
@@ -494,7 +494,7 @@ describe('app module', function () {
         })
       })
 
-      it('fetches normal icons', function (done) {
+      it('fetches normal icon', function (done) {
         app.getFileIcon(iconPath, { size: 'normal' }, function (err, icon) {
           const size = icon.getSize()
           assert.equal(err, null)
@@ -504,7 +504,7 @@ describe('app module', function () {
         })
       })
 
-      it('fetches large icons', function (done) {
+      it('fetches large icon', function (done) {
         if (process.platform === 'darwin') {
           return this.skip() // macOS does not support large icons
         }