diff --git a/cores/esp8266/cbuf.cpp b/cores/esp8266/cbuf.cpp
index 51aa013ba..cf539e6b0 100644
--- a/cores/esp8266/cbuf.cpp
+++ b/cores/esp8266/cbuf.cpp
@@ -37,7 +37,9 @@ size_t cbuf::resize(size_t newSize) {
 
     size_t available = getSize();
 
-    if((available > newSize) || (newSize == _size)) {
+	// not lose any data
+	// if data can be lost use remove or flush before resize
+    if((newSize < available) || (newSize == _size)) {
         return _size;
     }