$OpenBSD$
$NetBSD: patch-ac,v 1.1.1.1 2007/07/12 19:56:14 drochner Exp $

--- simgear/scene/sky/cloudfield.cxx.orig	Sat Dec  8 14:12:44 2007
+++ simgear/scene/sky/cloudfield.cxx	Mon Sep 21 17:07:48 2009
@@ -34,6 +34,7 @@
 
 #include STL_ALGORITHM
 #include <vector>
+#include <cmath>
 
 SG_USING_STD(vector);
 
@@ -180,7 +181,7 @@ void SGCloudField::reposition( sgVec3 p, sgVec3 up, do
         // this happens, lets just use the last known good course.
         // This is a hack, and it would probably be better to make
         // calc_gc_course_dist() more robust.
-        if ( isnan(course) ) {
+        if ( std::isnan(course) ) {
             course = last_course;
         } else {
             last_course = course;