$OpenBSD$
--- simgear/scene/sky/cloud.cxx.orig	Thu Dec 13 20:44:14 2007
+++ simgear/scene/sky/cloud.cxx	Mon Sep 21 13:37:49 2009
@@ -27,7 +27,7 @@
 #include <simgear/compiler.h>
 
 // #include <stdio.h>
-#include <math.h>
+#include <cmath>
 
 #include <plib/sg.h>
 #include <plib/ssg.h>
@@ -721,7 +721,7 @@ bool SGCloudLayer::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;