diff --git a/index.js b/index.js
index 6289d0b..a90e84e 100644
--- a/index.js
+++ b/index.js
@@ -6,7 +6,7 @@ let sugarss = require('sugarss')
 let vars = require('postcss-simple-vars')
 let glob = require('fast-glob')
 
-let MIXINS_GLOB = '*.{js,cjs,json,css,sss,pcss}'
+let MIXINS_GLOB = '*.{js,cjs,mjs,json,css,sss,pcss}'
 let IS_WIN = platform().includes('win32')
 
 function addMixin(helpers, mixins, rule, file) {
diff --git a/test/index.test.js b/test/index.test.js
index e68d68f..7d0e537 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -251,7 +251,7 @@ test('loads mixins from dir', async () => {
       },
       {
         dir: join(__dirname, 'mixins'),
-        glob: '*.{js,cjs,json,css,sss,pcss}',
+        glob: '*.{js,cjs,mjs,json,css,sss,pcss}',
         parent: '',
         type: 'dir-dependency'
       }
@@ -299,7 +299,7 @@ test('loads mixins from dir with parent options', async () => {
       },
       {
         dir: join(__dirname, 'mixins'),
-        glob: '*.{js,cjs,json,css,sss,pcss}',
+        glob: '*.{js,cjs,mjs,json,css,sss,pcss}',
         parent: '',
         type: 'dir-dependency'
       }