diff --git a/cpu/esp8266/sdk/ets_task.c b/cpu/esp8266/sdk/ets_task.c
index d9702315a76e54df22a3ae89437a0e9686f72ac5..62ddfc88b1ffb0f293d85ee94c10586951559561 100644
--- a/cpu/esp8266/sdk/ets_task.c
+++ b/cpu/esp8266/sdk/ets_task.c
@@ -181,7 +181,7 @@ uint32_t IRAM ets_post (uint32_t prio, ETSSignal sig, ETSParam par)
         system_soft_wdt_feed();
     }
 
-    if (ets_thread) {
+    if (ets_thread && irom_cache_enabled()) {
         thread_flags_set((thread_t*)ets_thread, THREAD_FLAG_ETS_THREAD);
     }