--- D:/Toolkits/Qt/qt-everywhere-enterprise-src-5.9.0-beta/qtwebengine/src/3rdparty/ninja/src/clparser.cc.bkp	Tue Mar 28 14:41:54 2017
+++ D:/Toolkits/Qt/qt-everywhere-enterprise-src-5.9.0-beta/qtwebengine/src/3rdparty/ninja/src/clparser.cc	Wed Apr 12 23:02:23 2017
@@ -53,7 +53,7 @@
 
 // static
 bool CLParser::IsSystemInclude(string path) {
-  transform(path.begin(), path.end(), path.begin(), ::tolower);
+  transform(path.begin(), path.end(), path.begin(), [](const char c) { return static_cast<char>(::tolower(c)); });
   // TODO: this is a heuristic, perhaps there's a better way?
   return (path.find("program files") != string::npos ||
           path.find("microsoft visual studio") != string::npos);
@@ -61,7 +61,7 @@
 
 // static
 bool CLParser::FilterInputFilename(string line) {
-  transform(line.begin(), line.end(), line.begin(), ::tolower);
+  transform(line.begin(), line.end(), line.begin(), [](const char c) { return static_cast<char>(::tolower(c)); });
   // TODO: other extensions, like .asm?
   return EndsWith(line, ".c") ||
       EndsWith(line, ".cc") ||