diff --git a/cssbeautify.js b/cssbeautify.js
index b4ae096..e5a7dfb 100644
--- a/cssbeautify.js
+++ b/cssbeautify.js
@@ -464,6 +464,9 @@
     } else if (typeof window === 'object') {
         // Browser loading.
         window.cssbeautify = cssbeautify;
+    } else if (self instanceof WorkerGlobalScope) {
+        // Web worker.
+        self.cssbeautify = cssbeautify;
     }
 
 }());