diff --git a/src/Bundler.js b/src/Bundler.js
index 1e0a14ddf32..0843580ede3 100644
--- a/src/Bundler.js
+++ b/src/Bundler.js
@@ -207,7 +207,9 @@ class Bundler extends EventEmitter {
         });
       });
     }
-
+    
+    this.emit('buildStart', this.entryFiles)
+    
     let isInitialBundle = !this.entryAssets;
     let startTime = Date.now();
     this.pending = true;