Index: src/cmd/collide_map.h
--- src/cmd/collide_map.h.orig
+++ src/cmd/collide_map.h
@@ -35,6 +35,7 @@
 #include <limits>
 #endif
 #include <vector>
+#include <cmath>
 /* Arbitrarily use Set for ALL PLATFORMS -hellcatv */
 class Unit;
 class Bolt;
@@ -61,7 +62,7 @@ class Collidable { (public)
             position = QVector( 0, 0, 0 );      //hack for now
 
 #else
-        if (ISNAN(getKey())) {
+        if (std::isnan(getKey())) {
             position = QVector(0, 0, 0);
         }      //hack for now
 #endif
@@ -105,7 +106,7 @@ class Collidable { (public)
 #if defined(__APPLE__) && defined(__MACH__)
                         !FINITE( radius )
 #else
-                        ISNAN(radius)
+                        std::isnan(radius)
 #endif
                         || radius >= -FLT_MIN) {
             radius = -FLT_MIN * 2;
@@ -223,7 +224,7 @@ inline void init_null_collide_iter()
 
 inline bool is_null( const CollideMap::iterator &it )
 {
-    return ISNAN( (**it).radius );
+    return std::isnan( (**it).radius );
 }
 
 inline void set_null( CollideMap::iterator &it )
