diff --git a/.gitignore b/.gitignore
index de4b972193..f693b94bf0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -263,6 +263,7 @@ lcov*.info
 /lib/prism/dsl.rb
 /lib/prism/mutation_compiler.rb
 /lib/prism/node.rb
+/lib/prism/reflection.rb
 /lib/prism/serialize.rb
 /lib/prism/visitor.rb
 /prism/api_node.c