--- embedaddon/readline/examples/autoconf/RL_LIB_READLINE_VERSION	2014/07/30 08:16:46	1.1.1.1
+++ embedaddon/readline/examples/autoconf/RL_LIB_READLINE_VERSION	2021/03/17 01:01:01	1.1.1.2
@@ -35,6 +35,7 @@ AC_CACHE_VAL(ac_cv_rl_version,
 [AC_TRY_RUN([
 #include <stdio.h>
 #include <readline/readline.h>
+#include <stdlib.h>
 
 extern int rl_gnu_readline_p;