diff --git a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
index b06bd071..c06563fc 100644
--- a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
+++ b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
@@ -32,6 +32,7 @@
 #include "sdkconfig.h"
 
 #ifndef __ASSEMBLER__
+#include <stdlib.h>
 #include "rom/ets_sys.h"
 #endif