diff --git a/ruby.spec b/ruby.spec
index e4da346..07d7b86 100644
--- a/ruby.spec
+++ b/ruby.spec
@@ -7,7 +7,9 @@
 
 %global ruby_version %{major_minor_version}.%{teeny_version}
 %global ruby_version_patch_level %{major_minor_version}.%{teeny_version}.%{patch_level}
-# Ruby 2.0 keeps the abi Ruby 1.9.1 compatible.
+# TODO: Fix ruby_api for official release according to
+# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/48984
+# It is kept at 1.9.1 just for testing. All dependent libraries need rebuild.
 # %%global ruby_abi %%{major_minor_version}.0
 %global ruby_abi 1.9.1