diff --git a/doc/api/mruby/re.h.md b/doc/api/mruby/re.h.md
index e69de29bb..01e18c6a5 100644
--- a/doc/api/mruby/re.h.md
+++ b/doc/api/mruby/re.h.md
@@ -0,0 +1,3 @@
+#### Macros
+### REGEXP_CLASS
+A string with the name of the REGEXP class.