Index: code/windows_stub/config.h
===================================================================
--- code/windows_stub/config.h	(revision 9409)
+++ code/windows_stub/config.h	(working copy)
@@ -277,7 +277,7 @@
 char *strnset( char *string, int fill, size_t count);
 
 // other stuff
-#define _isnan(f)     isnan(f)
+#define _isnan(f)     std::isnan(f)
 #define _hypot(x, y)  hypot(x, y)
 
 int MulDiv(int number, int numerator, int denominator);