diff --git a/effects/mousemark.cpp b/effects/mousemark.cpp
index bcfd4a4313..39542343f9 100644
--- a/effects/mousemark.cpp
+++ b/effects/mousemark.cpp
@@ -157,7 +157,7 @@ void MouseMarkEffect::clearLast()
 MouseMarkEffect::Mark MouseMarkEffect::createArrow( QPoint arrow_start, QPoint arrow_end )
     {
     Mark ret;
-    double angle = atan2( arrow_end.y() - arrow_start.y(), arrow_end.x() - arrow_start.x());
+    double angle = atan2( (double) (arrow_end.y() - arrow_start.y()), (double) (arrow_end.x() - arrow_start.x()));
     ret += arrow_start + QPoint( 50 * cos( angle + M_PI / 6 ),
         50 * sin( angle + M_PI / 6 )); // right one
     ret += arrow_start;