diff --git a/include/stdlib.h b/include/stdlib.h
index b5a5b3028584c..f3ede5d9c6f18 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -183,7 +183,7 @@ void      _Exit(int status) noreturn_function;
  * standards compatibility.
  */
 
-#ifndef __KERNEL__
+#if !defined(__KERNEL__) || defined(CONFIG_BUILD_FLAT)
 int       system(FAR const char *cmd);
 #endif