diff --git a/configure.ac b/configure.ac
index ec64637b186b..3229e0dac040 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1834,6 +1834,7 @@ AC_DEFINE([HAVE_BUILD_DEFS_H], [1],
 
 PHP_ADD_BUILD_DIR([
   main
+  main/io
   main/poll
   main/streams
   scripts