diff --git a/lcl/include/font.inc b/lcl/include/font.inc
index 6d622f2ec4..e667d4c215 100644
--- a/lcl/include/font.inc
+++ b/lcl/include/font.inc
@@ -771,7 +771,7 @@ begin
     try
       FreeHandle;
       inherited SetSize(AValue);
-      FHeight := - Round(AValue * FPixelsPerInch / 72);
+      FHeight := -MulDiv(AValue, FPixelsPerInch, 72);
       if IsFontNameXLogicalFontDesc(Name) then
         Name:=ClearXLFDHeight(Name);
       Changed;
@@ -824,7 +824,7 @@ procedure TFont.SetHeight(Value: Integer);
 begin
   if FHeight=Value then exit;
   // set Size first. This will set FHeight to a rounded equivalent
-  Size := -Round(Value*72/FPixelsPerInch);
+  Size := -MulDiv(Value, 72, FPixelsPerInch);
   // store the real FHeight
   FHeight:=Value;
 end;