diff --git a/lcl/interfaces/gtk2/gtk2winapi.inc b/lcl/interfaces/gtk2/gtk2winapi.inc
index 0d58fce95b..51a98faf5b 100644
--- a/lcl/interfaces/gtk2/gtk2winapi.inc
+++ b/lcl/interfaces/gtk2/gtk2winapi.inc
@@ -5347,10 +5347,12 @@ begin
     SM_CXBORDER:
       begin
         //DebugLn('Trace:TODO: [TGtk2WidgetSet.GetSystemMetrics] --> SM_CXBORDER         ');
+        Result := Max(FCachedBorderSize, 0);
       end;
     SM_CYBORDER:
       begin
         //DebugLn('Trace:TODO: [TGtk2WidgetSet.GetSystemMetrics] --> SM_CYBORDER         ');
+        Result := Max(FCachedBorderSize, 0);
       end;
     SM_CXCURSOR,
     SM_CYCURSOR: