diff --git a/m4/jm-macros.m4 b/m4/jm-macros.m4
index b9f9a876f..f8fbffa49 100644
--- a/m4/jm-macros.m4
+++ b/m4/jm-macros.m4
@@ -27,4 +27,5 @@ AC_DEFUN(jm_MACROS,
   AC_REQUIRE([jm_FUNC_MALLOC])
   AC_REQUIRE([jm_FUNC_READDIR])
   AC_REQUIRE([jm_FUNC_MEMCMP])
+  AC_REQUIRE([jm_FUNC_GLIBC_UNLOCKED_IO])
 ])