diff -rupN gimagereader-3.1.2/qt/src/Displayer.cc gimagereader-3.1.2-new/qt/src/Displayer.cc
--- gimagereader-3.1.2/qt/src/Displayer.cc	2015-06-30 17:36:39.000000000 +0200
+++ gimagereader-3.1.2-new/qt/src/Displayer.cc	2016-02-04 09:32:25.701479818 +0100
@@ -32,6 +32,7 @@
 #include <QWheelEvent>
 #include <tesseract/baseapi.h>
 #include <cassert>
+#include <cmath>
 
 
 class GraphicsScene : public QGraphicsScene