diff --git a/cores/esp8266/Esp.cpp b/cores/esp8266/Esp.cpp
index cd3b16f6a..299a97996 100644
--- a/cores/esp8266/Esp.cpp
+++ b/cores/esp8266/Esp.cpp
@@ -1,8 +1,8 @@
-/* 
+/*
  Esp.cpp - ESP8266-specific APIs
  Copyright (c) 2015 Ivan Grokhotkov. All rights reserved.
  This file is part of the esp8266 core for Arduino environment.
- 
+
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
@@ -32,7 +32,7 @@ extern struct rst_info resetInfo;
 
 //#define DEBUG_SERIAL Serial
 
-    
+
 /**
  * User-defined Literals
  *  usage:
@@ -92,7 +92,7 @@ void EspClass::wdtEnable(WDTO_t timeout_ms)
 
 void EspClass::wdtDisable(void)
 {
-    /// Please don’t stop software watchdog too long (less than 6 seconds),
+    /// Please don't stop software watchdog too long (less than 6 seconds),
     /// otherwise it will trigger hardware watchdog reset.
     system_soft_wdt_stop();
 }
@@ -102,13 +102,15 @@ void EspClass::wdtFeed(void)
 
 }
 
+extern "C" void esp_yield();
+
 void EspClass::deepSleep(uint32_t time_us, WakeMode mode)
 {
-	system_deep_sleep_set_option(static_cast<int>(mode));
- 	system_deep_sleep(time_us);
+    system_deep_sleep_set_option(static_cast<int>(mode));
+    system_deep_sleep(time_us);
+    esp_yield();
 }
 
-extern "C" void esp_yield();
 extern "C" void __real_system_restart_local();
 void EspClass::reset(void)
 {
@@ -119,9 +121,6 @@ void EspClass::restart(void)
 {
     system_restart();
     esp_yield();
-    // todo: provide an alternative code path if this was called
-    // from system context, not from continuation
-    // (implement esp_is_cont_ctx()?)
 }
 
 uint16_t EspClass::getVcc(void)
@@ -333,7 +332,7 @@ uint32_t EspClass::getSketchSize() {
     DEBUG_SERIAL.printf("num_segments=%u\r\n", image_header.num_segments);
 #endif
     for (uint32_t section_index = 0;
-        section_index < image_header.num_segments; 
+        section_index < image_header.num_segments;
         ++section_index)
     {
         section_header_t section_header = {0};
@@ -395,8 +394,7 @@ bool EspClass::updateSketch(Stream& in, uint32_t size, bool restartOnFail, bool
 
 #ifdef DEBUG_SERIAL
     DEBUG_SERIAL.println("Update SUCCESS");
-#endif  
+#endif
     if(restartOnSuccess) ESP.restart();
     return true;
 }
-
diff --git a/cores/esp8266/core_esp8266_main.cpp b/cores/esp8266/core_esp8266_main.cpp
index 67c3f3802..a953c8782 100644
--- a/cores/esp8266/core_esp8266_main.cpp
+++ b/cores/esp8266/core_esp8266_main.cpp
@@ -74,7 +74,9 @@ extern "C" void abort() {
 }
 
 extern "C" void esp_yield() {
-    cont_yield(&g_cont);
+    if (cont_can_yield(&g_cont)) {
+        cont_yield(&g_cont);
+    }
 }
 
 extern "C" void esp_schedule() {