1 files changed, 3 insertions, 1 deletions
diff --git a/src/mainwindow.cc b/src/mainwindow.cc
index cd322b9..27452ce 100644
--- a/src/mainwindow.cc
+++ b/src/mainwindow.cc
@@ -37,6 +37,8 @@
 #include <qlayout.h>
 #include <qstatusbar.h>
 
+#include <math.h>
+
 //#include "mgui_alert.h"
 //#include "mgui_datasocket.h"
 
@@ -218,7 +220,7 @@ void MainWindow::createGui()
 void MainWindow::redraw_edge()
 {
   rec_edge_counter += SPEED;
-  float val = abs(sin(rec_edge_counter));
+  float val = fabs(sin(rec_edge_counter));
   img_recedge->setBackgroundColor(QColor((int) ((255 - GREY) * val + GREY),
                                          (int) (GREY - (GREY * val)),
                                          (int) (GREY - (GREY * val))));