diff --git a/lib/generator.rb b/lib/generator.rb
index 241987faba..03ff0962d4 100644
--- a/lib/generator.rb
+++ b/lib/generator.rb
@@ -76,7 +76,7 @@ class Generator
       begin
         @block.call(self)
       rescue
-        @main_thread.raise
+        @main_thread.raise $!
       ensure
         @main_thread.wakeup
       end