diff --git a/src/WebHandlers.cpp b/src/WebHandlers.cpp
index f59d262..599fae2 100644
--- a/src/WebHandlers.cpp
+++ b/src/WebHandlers.cpp
@@ -22,7 +22,7 @@
 #include "WebHandlerImpl.h"
 
 AsyncStaticWebHandler::AsyncStaticWebHandler(const char* uri, FS& fs, const char* path, const char* cache_control)
-  : _fs(fs), _uri(uri), _path(path), _default_file("index.htm"), _cache_control(cache_control), _last_modified(NULL)
+  : _fs(fs), _uri(uri), _path(path), _default_file("index.htm"), _cache_control(cache_control), _last_modified("")
 {
   // Ensure leading '/'
   if (_uri.length() == 0 || _uri[0] != '/') _uri = "/" + _uri;