diff --git a/.res/labels.merge3.yml b/.res/labels.merge3.yml
new file mode 100644
index 00000000..ed1b4adb
--- /dev/null
+++ b/.res/labels.merge3.yml
@@ -0,0 +1 @@
+_extends: ghaction-github-labeler:.res/labels.merge1.yml
diff --git a/__tests__/labeler.test.ts b/__tests__/labeler.test.ts
index 64e8f684..d7b73bb2 100644
--- a/__tests__/labeler.test.ts
+++ b/__tests__/labeler.test.ts
@@ -174,4 +174,27 @@ describe('run', () => {
     expect(fileLabels[1]).toEqual(expect.objectContaining({name: ':bug: bug', description: 'Damn bugs'}));
     expect(() => labeler.run()).not.toThrow();
   });
+  it('extends', async () => {
+    const input = <Inputs>{
+      githubToken: process.env.GITHUB_TOKEN || 'test',
+      yamlFile: '.res/labels.merge3.yml',
+      skipDelete: true,
+      dryRun: true,
+      exclude: []
+    };
+    nock('https://api.github.com').get('/repos/crazy-max/ghaction-github-labeler/labels').reply(200, labelsFixture());
+
+    nock('https://api.github.com')
+      .get(`/repos/crazy-max/ghaction-github-labeler/contents/${encodeURIComponent(input.yamlFile as string)}`)
+      .reply(200, configFixture(input.yamlFile as string));
+
+    nock('https://api.github.com')
+      .get(`/repos/crazy-max/ghaction-github-labeler/contents/${encodeURIComponent('.res/labels.merge1.yml')}`)
+      .reply(200, configFixture('.res/labels.merge1.yml'));
+
+    const labeler = new Labeler(input);
+    const fileLabels = await labeler.fileLabels;
+    expect(fileLabels.length).toBe(15);
+    expect(() => labeler.run()).not.toThrow();
+  });
 });
diff --git a/dist/index.js b/dist/index.js
index cbb8fc96..5b137141 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -276,7 +276,9 @@ class Labeler {
                     const output = [];
                     configs
                         .map(config => {
-                        const labels = config.labels ? config.labels : config;
+                        let labels = config.labels ? config.labels : config;
+                        if (Object.keys(labels).length === 0)
+                            labels = undefined;
                         return { labels: labels || [] };
                     })
                         .map(config => {
diff --git a/src/labeler.ts b/src/labeler.ts
index 9394c473..57723970 100644
--- a/src/labeler.ts
+++ b/src/labeler.ts
@@ -211,7 +211,8 @@ export class Labeler {
         const output = [] as Label[];
         configs
           .map(config => {
-            const labels = config.labels ? config.labels : config;
+            let labels = config.labels ? config.labels : config;
+            if (Object.keys(labels).length === 0) labels = undefined;
             return {labels: labels || []};
           })
           .map(config => {