diff --git a/format/README.md b/format/README.rst
similarity index 98%
rename from format/README.md
rename to format/README.rst
index 6da844549e640..0eaad49b7e394 100644
--- a/format/README.md
+++ b/format/README.rst
@@ -22,4 +22,4 @@ This folder contains binary protocol definitions for the Arrow columnar format
 and other parts of the project, like the Flight RPC framework.
 
 For documentation about the Arrow format, see the `docs/source/format`
-directory.
\ No newline at end of file
+directory.