diff -up kholidays-15.12.1/src/sunriseset.cpp.gcc6 kholidays-15.12.1/src/sunriseset.cpp
--- kholidays-15.12.1/src/sunriseset.cpp.gcc6	2015-11-21 18:49:24.000000000 -0600
+++ kholidays-15.12.1/src/sunriseset.cpp	2016-02-11 08:31:39.554683739 -0600
@@ -23,6 +23,7 @@
 */
 
 #include "sunriseset.h"
+#include <math.h>
 #include <cmath>
 static const double PI = 3.14159265358979323846;
 static const double MaxLat = 89.99;