diff --git a/cores/esp8266/Updater.cpp b/cores/esp8266/Updater.cpp
index 740ec3202..728700c2f 100644
--- a/cores/esp8266/Updater.cpp
+++ b/cores/esp8266/Updater.cpp
@@ -121,6 +121,9 @@ size_t UpdaterClass::write(uint8_t *data, size_t len){
   if(hasError())
     return 0;
   
+  if(len > remaining())
+    len = remaining();
+  
   while((_bufferLen + left) > FLASH_SECTOR_SIZE){
     size_t toBuff = FLASH_SECTOR_SIZE - _bufferLen;
     memcpy(_buffer + _bufferLen, data + (len - left), toBuff);