diff --git a/cores/esp8266/Esp.cpp b/cores/esp8266/Esp.cpp
index 4d9d8b033..504cf028d 100644
--- a/cores/esp8266/Esp.cpp
+++ b/cores/esp8266/Esp.cpp
@@ -414,6 +414,13 @@ bool EspClass::updateSketch(Stream& in, uint32_t size) {
             return false;
         }
 
+        if(addr == freeSpaceStart) {
+            // check for valid first magic byte
+            if(*((uint8 *) buffer.get()) != 0xE9) {
+                return false;
+            }
+        }
+
         noInterrupts();
         rc = SPIWrite(addr, buffer.get(), willRead);
         interrupts();
diff --git a/libraries/ESP8266httpUpdate/src/ESP8266httpUpdate.cpp b/libraries/ESP8266httpUpdate/src/ESP8266httpUpdate.cpp
index 118ec894f..ef48087e1 100644
--- a/libraries/ESP8266httpUpdate/src/ESP8266httpUpdate.cpp
+++ b/libraries/ESP8266httpUpdate/src/ESP8266httpUpdate.cpp
@@ -72,6 +72,9 @@ t_httpUpdate_return ESP8266HTTPUpdate::update(const char *host, uint16_t port, c
     req += "\r\n"
             "x-ESP8266-chip-size: ";
     req += ESP.getFlashChipRealSize();
+    req += "\r\n"
+           "x-ESP8266-sdk-version: ";
+    req += ESP.getSdkVersion();
 
     if(current_version[0] != 0x00) {
         req += "\r\n"