diff --git a/src/classes/PPrepFourier.cpp b/src/classes/PPrepFourier.cpp
index cf077229..907689e9 100644
--- a/src/classes/PPrepFourier.cpp
+++ b/src/classes/PPrepFourier.cpp
@@ -27,6 +27,8 @@
  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  ***************************************************************************/
 
+#include <cmath>
+
 #include "PPrepFourier.h"
 
 //--------------------------------------------------------------------------