diff --git a/ext/project_data.yaml b/ext/project_data.yaml
index 556d84050d4..4597508f4c1 100644
--- a/ext/project_data.yaml
+++ b/ext/project_data.yaml
@@ -6,3 +6,15 @@ gem_rdoc_options:
   - --main
   - README.md
   - --line-numbers
+# Array of files to include when building source tarballs
+files:
+  - '[A-Z]*'
+  - install.rb
+  - bin
+  - lib
+  - conf
+  - man
+  - examples
+  - ext
+  - tasks
+  - locales