--- cmath.h.orig	Fri Dec 12 21:33:45 2003
+++ cmath.h	Thu Jan 22 22:22:45 2004
@@ -175,5 +175,12 @@
 #endif
 
 #if !defined(HAVE_ISNAN_DECL) && !defined(HAVE_ISNAN_MACRO)
+#ifdef __FreeBSD__
+#  include <sys/param.h>
+#  if __FreeBSD_version < 500100
+extern int isnan ( double x );
+#  endif
+#endif
+#else
 extern int isnan ( double x );
 #endif
