--- src/slicer/poly.cpp.orig	2015-12-28 07:54:32.774722105 +0100
+++ src/slicer/poly.cpp	2015-12-28 07:54:41.188055896 +0100
@@ -225,7 +225,7 @@
   // Start with first vertex as closest
   uint nindex = 0;
   mindist = (vertices[0]-p).squared_length();
-  if (isnan(mindist)) { // for infinity point p return point 0 and distance 0
+  if (std::isnan(mindist)) { // for infinity point p return point 0 and distance 0
     mindist = 0.;
     return 0;
   }
--- src/slicer/printlines.cpp.orig	2015-12-28 07:54:05.814720635 +0100
+++ src/slicer/printlines.cpp	2015-12-28 07:54:19.821388065 +0100
@@ -240,7 +240,7 @@
   if (abs(absolute_extrusion) < 0.00001)
     travel_speed = max(minspeed, speed); // in case speed is too low
 
-  if (!isnan(absolute_extrusion))
+  if (!std::isnan(absolute_extrusion))
     // allowed to push/pull at arbitrary speed
     extrudedMaterial += absolute_extrusion;
   else
@@ -335,7 +335,7 @@
     else
       factor = 1./newlines.size();
     newlines[i].absolute_extrusion *= factor;
-    assert(!isnan(newlines[i].absolute_extrusion));
+    assert(!std::isnan(newlines[i].absolute_extrusion));
 
   }
   return newlines;