diff --git a/but_calibration_camera_velodyne/include/but_calibration_camera_velodyne/Calibration.h b/but_calibration_camera_velodyne/include/but_calibration_camera_velodyne/Calibration.h
index 519e48e..f38e059 100644
--- a/but_calibration_camera_velodyne/include/but_calibration_camera_velodyne/Calibration.h
+++ b/but_calibration_camera_velodyne/include/but_calibration_camera_velodyne/Calibration.h
@@ -4,6 +4,7 @@
 #include <cstdlib>
 #include <cstdio>
 #include <iostream>
+#include <cmath>
 
 #include "opencv2/opencv.hpp"
 #include <pcl/point_cloud.h>
@@ -50,7 +51,7 @@ class Calibration6DoF
 
   bool isGood()
   {
-    return !isnan(value);
+    return !std::isnan(value);
   }
 
   void set(float x, float y, float z, float x_r, float y_r, float z_r, float val)