diff --git a/client/src/proxguiqt.cpp b/client/src/proxguiqt.cpp
index aa74a83fd..52f0a8955 100644
--- a/client/src/proxguiqt.cpp
+++ b/client/src/proxguiqt.cpp
@@ -697,10 +697,15 @@ void Plot::wheelEvent(QWheelEvent *event) {
         x += GraphStart;
 // event->angleDelta doesn't exist in QT4, both exist in 5.12.8 and 5.14.2 and event->delta doesn't exist in 5.15.0
 #if QT_VERSION >= 0x050d00
-        Zoom(1.0 - (float)event->angleDelta().y() / (120 / zoom_offset), x);
+        float delta = event->angleDelta().y();
 #else
-        Zoom(1.0 - (float)event->delta() / (120 / zoom_offset), x);
+        float delta = event->delta();
 #endif
+        if (delta < 0) {
+            Zoom(1.0 - (float)delta / (120 / zoom_offset), x);
+        } else {
+            Zoom(1.0 / (1.0 + (float)delta / (120 / zoom_offset)), x);
+        }
     } else {
 #if QT_VERSION >= 0x050d00
         Move(PageWidth * (-(float)event->angleDelta().y() / (120 / move_offset)));