diff --git a/lib/rspec_api_documentation/writers/append_json_writer.rb b/lib/rspec_api_documentation/writers/append_json_writer.rb
index 5eae1f7b..8cdeaea9 100644
--- a/lib/rspec_api_documentation/writers/append_json_writer.rb
+++ b/lib/rspec_api_documentation/writers/append_json_writer.rb
@@ -19,7 +19,7 @@ def self.clear_docs(docs_dir)
       end
     end
 
-    class AppendJsonIndex < JsonIndex
+    class AppendJsonIndex < JSONIndex
       def initialize(index, configuration, existing_index_hash = nil)
         @index = index
         @configuration = configuration