$NetBSD$

--- simgear/scene/sky/cloud.cxx.orig	2010-02-17 15:39:21.000000000 +0000
+++ simgear/scene/sky/cloud.cxx
@@ -28,7 +28,7 @@
 
 #include <sstream>
 
-#include <math.h>
+#include <cmath>
 
 #include <simgear/structure/OSGVersion.hxx>
 #include <osg/AlphaFunc>
@@ -695,7 +695,7 @@ bool SGCloudLayer::reposition( const SGV
         // 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;
