diff --git a/src/qt/window.cpp b/src/qt/window.cpp
index 942613eeb7..a39a37540c 100644
--- a/src/qt/window.cpp
+++ b/src/qt/window.cpp
@@ -969,7 +969,7 @@ bool wxWindowQt::IsTransparentBackgroundSupported(wxString* WXUNUSED(reason)) co
 bool wxWindowQt::SetTransparent(wxByte alpha)
 {
     // For Qt, range is between 1 (opaque) and 0 (transparent)
-    GetHandle()->setWindowOpacity(1 - alpha/255.0);
+    GetHandle()->setWindowOpacity(alpha/255.0);
     return true;
 }