diff --git a/ext/tuple/extconf.rb b/ext/tuple/extconf.rb
index ce4e688..3b2b1ac 100644
--- a/ext/tuple/extconf.rb
+++ b/ext/tuple/extconf.rb
@@ -8,7 +8,7 @@ when /\A1\.9/
 when /\A2\.(0|1)/
   $CFLAGS += ' -DRUBY_2_x_x'
   $CFLAGS += ' -DRUBY_2_1_x'
-when /\A2\.2/
+when /\A2\.(2|3|4)/
   $CFLAGS += ' -DRUBY_2_x_x'
   $CFLAGS += ' -DRUBY_2_2_x'
 else