diff --git a/lcl/interfaces/qt/qtwidgets.pas b/lcl/interfaces/qt/qtwidgets.pas
index 4b60f1d781..af24374591 100644
--- a/lcl/interfaces/qt/qtwidgets.pas
+++ b/lcl/interfaces/qt/qtwidgets.pas
@@ -637,6 +637,7 @@ type
   public
     function CheckState: QtCheckState;
     procedure setCheckState(state: QtCheckState);
+    procedure setTriState(AAllowGrayed: Boolean);
   public
     procedure AttachEvents; override;
     procedure DetachEvents; override;
@@ -5937,6 +5938,11 @@ begin
   QCheckBox_setCheckState(QCheckBoxH(Widget), state);
 end;
 
+procedure TQtCheckBox.setTriState(AAllowGrayed: Boolean);
+begin
+  QCheckBox_setTristate(QCheckBoxH(Widget), AAllowGrayed);
+end;
+
 procedure TQtCheckBox.AttachEvents;
 begin
   inherited AttachEvents;
diff --git a/lcl/interfaces/qt/qtwsstdctrls.pp b/lcl/interfaces/qt/qtwsstdctrls.pp
index c1158fba5c..645061097e 100644
--- a/lcl/interfaces/qt/qtwsstdctrls.pp
+++ b/lcl/interfaces/qt/qtwsstdctrls.pp
@@ -1175,6 +1175,7 @@ begin
   //enclose the call between Begin/EndUpdate to avoid send LM_CHANGE message
   QtCheckBox := TQtCheckBox(ACustomCheckBox.Handle);
   QtCheckBox.BeginUpdate;
+  QtCheckBox.setTriState(ACustomCheckBox.AllowGrayed);
   case NewState of
     cbGrayed: QtCheckBox.setCheckState(QtPartiallyChecked);
     cbChecked: QtCheckBox.setCheckState(QtChecked);
@@ -1196,6 +1197,7 @@ var
   QtCheckBox: TQtCheckBox;
 begin
   QtCheckBox := TQtCheckBox.Create(AWinControl, AParams);
+  QtCheckBox.setTriState(TCustomCheckBox(AWinControl).AllowGrayed);
   QtCheckBox.AttachEvents;
 
   Result := TLCLIntfHandle(QtCheckBox);