diff --git a/lcl/interfaces/gtk/gtkproc.inc b/lcl/interfaces/gtk/gtkproc.inc
index 534c11a3cd..6c5f5de42b 100644
--- a/lcl/interfaces/gtk/gtkproc.inc
+++ b/lcl/interfaces/gtk/gtkproc.inc
@@ -360,25 +360,25 @@ begin
   Result:=-1;
 end;
 
-function RectFromGdkRect(AGdkRect: TGdkRectangle): TRect;
+function RectFromGdkRect(const AGdkRect: TGdkRectangle): TRect;
 begin
-  with Result, AGdkRect do
+  with Result do
   begin
-    Left := x;
-    Top := y;
-    Right := Width + x;
-    Bottom := Height + y;
+    Left := AGdkRect.x;
+    Top := AGdkRect.y;
+    Right := AGdkRect.Width + AGdkRect.x;
+    Bottom := AGdkRect.Height + AGdkRect.y;
   end;
 end;
 
-function GdkRectFromRect(R: TRect): TGdkRectangle;
+function GdkRectFromRect(const R: TRect): TGdkRectangle;
 begin
-  with Result, R do
+  with Result do
   begin
-    x := Left;
-    y := Top;
-    width := Right-Left;
-    height := Bottom-Top;
+    x := R.Left;
+    y := R.Top;
+    width := R.Right-R.Left;
+    height := R.Bottom-R.Top;
   end;
 end;
 
diff --git a/lcl/interfaces/gtk/gtkproc.pp b/lcl/interfaces/gtk/gtkproc.pp
index 041d146b01..482f4ef631 100644
--- a/lcl/interfaces/gtk/gtkproc.pp
+++ b/lcl/interfaces/gtk/gtkproc.pp
@@ -277,8 +277,8 @@ var
 //==============================================================================
 // functions
 
-function RectFromGdkRect(AGdkRect: TGdkRectangle): TRect;
-function GdkRectFromRect(R: TRect): TGdkRectangle;
+function RectFromGdkRect(const AGdkRect: TGdkRectangle): TRect;
+function GdkRectFromRect(const R: TRect): TGdkRectangle;
 function AlignToGtkAlign(Align: TAlignment): gfloat;
 {$ifdef gtk2}
 function GtkScrollTypeToScrollCode(ScrollType: TGtkScrollType): LongWord;