diff --git a/winsup/mingw/ChangeLog b/winsup/mingw/ChangeLog
index 4268822f3..89499cbe6 100644
--- a/winsup/mingw/ChangeLog
+++ b/winsup/mingw/ChangeLog
@@ -1,3 +1,8 @@
+2003-10-27  Danny Smith  <dannysmith@users.sourceforge.net>
+
+	* include/math.h: Guard ISO C99 additions with __cplusplus
+	not __GLIBCPP__.
+
 2003-10-21  Danny Smith  <dannysmith@users.sourceforge.net>
 
 	* include/_mingw.h: Define __attribute__((x)) to nothing
diff --git a/winsup/mingw/include/math.h b/winsup/mingw/include/math.h
index af6a40f22..96405229d 100644
--- a/winsup/mingw/include/math.h
+++ b/winsup/mingw/include/math.h
@@ -241,7 +241,7 @@ _CRTIMP int __cdecl fpclass (double);
 
 #ifndef __NO_ISOCEXT
 #if (defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) \
-	|| !defined __STRICT_ANSI__ || defined __GLIBCPP__
+	|| !defined __STRICT_ANSI__ || defined __cplusplus
 
 #define NAN (0.0F/0.0F)
 #define HUGE_VALF (1.0F/0.0F)