diff --git a/src/slic3r/GUI/IMSlider.cpp b/src/slic3r/GUI/IMSlider.cpp
index 3bfc26cd11..15b1237410 100644
--- a/src/slic3r/GUI/IMSlider.cpp
+++ b/src/slic3r/GUI/IMSlider.cpp
@@ -1470,10 +1470,11 @@ void IMSlider::on_mouse_wheel(wxMouseEvent& evt) {
 
     ImGuiWrapper& imgui = *wxGetApp().imgui();
 
-    float wheel = 0.0f;
-    wheel = evt.GetWheelRotation() > 0 ? 1.0f : -1.0f;
+    float wheel = evt.GetWheelRotation();
+    // mac trackpads trigger this event with value 0 when right-clicking with two fingers
     if (wheel == 0.0f)
         return;
+    wheel = wheel > 0 ? 1.0f : -1.0f;
 
 #ifdef __WXOSX__
     if (wxGetKeyState(WXK_SHIFT)) {