diff --git a/src/AsyncEventSource.cpp b/src/AsyncEventSource.cpp
index 3a2f9ea..1c34c85 100644
--- a/src/AsyncEventSource.cpp
+++ b/src/AsyncEventSource.cpp
@@ -19,7 +19,9 @@
 */
 #include "Arduino.h"
 #include "AsyncEventSource.h"
-#include <rom/ets_sys.h>
+#ifndef ESP8266
+  #include <rom/ets_sys.h>
+#endif
 
 static String generateEventMessage(const char *message, const char *event, uint32_t id, uint32_t reconnect){
   String ev;