diff --git a/components/richmemo/richmemo.pas b/components/richmemo/richmemo.pas
index 3998cfe40..eaa512138 100644
--- a/components/richmemo/richmemo.pas
+++ b/components/richmemo/richmemo.pas
@@ -845,16 +845,24 @@ var
   j : Integer;
   l : Integer;
   p : TFontParams;
+  allowInternalChange: Boolean;
+  fp : TFontParams;
+const
+  AllFontStyles : TFontStyles = [fsBold, fsItalic, fsUnderline, fsStrikeOut];
 begin
   if not HandleAllocated then HandleNeeded;
 
   if (ModifyMask = []) or (TextLength = 0) then Exit;
 
-  if TWSCustomRichMemoClass(WidgetSetClass).isInternalChange(Self, ModifyMask) then
+  allowInternalChange:=(not (tmm_Styles in ModifyMask)) or (AddFontStyle+RemoveFontStyle=AllFontStyles);
+
+  if allowInternalChange and (TWSCustomRichMemoClass(WidgetSetClass).isInternalChange(Self, ModifyMask)) then
   begin
     // more effecient from OS view
+    fp:=fnt;
+    if tmm_Styles in ModifyMask then  fp.Style:=AddFontStyle;
     TWSCustomRichMemoClass(WidgetSetClass).SetTextAttributesInternal(Self,
-      TextStart, TextLength, ModifyMask, fnt);
+      TextStart, TextLength, ModifyMask, fp);
     Exit;
   end;
 
diff --git a/components/richmemo/win32/win32richmemoproc.pas b/components/richmemo/win32/win32richmemoproc.pas
index ca958da51..b9cd19a36 100644
--- a/components/richmemo/win32/win32richmemoproc.pas
+++ b/components/richmemo/win32/win32richmemoproc.pas
@@ -383,6 +383,8 @@ class function TRichEditManager.SetSelectedTextStyle(RichEditWnd: Handle;
 var
   w : WPARAM;
   fmt : TCHARFORMAT2;
+const
+  CFM_STYLESONLY = CFM_BOLD or CFM_ITALIC or CFM_UNDERLINE or CFM_STRIKEOUT or CFM_SUBSCRIPT or CFM_SUPERSCRIPT;
 begin
   if RichEditWnd = 0 then begin
     Result := false;
@@ -411,7 +413,7 @@ begin
   end;
 
   if not useMask or (tmm_Styles in AModifyMask) then begin
-    fmt.dwMask := fmt.dwMask or CFM_EFFECTS or CFM_SUBSCRIPT or CFM_SUPERSCRIPT;
+    fmt.dwMask := fmt.dwMask or CFM_STYLESONLY;
     fmt.dwEffects := FontStylesToEffects(Params.Style) or VScriptPosToEffects(Params.VScriptPos);
   end;