diff --git a/lib/opal/source_map.rb b/lib/opal/source_map.rb
index <HASH>..<HASH> 100644
--- a/lib/opal/source_map.rb
+++ b/lib/opal/source_map.rb
@@ -28,9 +28,8 @@ module Opal
 
             mapping = ::SourceMap::Mapping.new(
               source_file,
-              source_offset,
               generated_offset,
-              source_code
+              source_offset
             )
           end
Fix Ruby source map mappings generation

1. The code passed should have been the original code, but we only have access to the generated code

2. The order was wrong, first it needs the generated offset and then the source one