diff --git a/lcl/interfaces/gtk3/gtk3objects.pas b/lcl/interfaces/gtk3/gtk3objects.pas
index ff9fb8440b..bbfd488cc7 100644
--- a/lcl/interfaces/gtk3/gtk3objects.pas
+++ b/lcl/interfaces/gtk3/gtk3objects.pas
@@ -1937,7 +1937,8 @@ end;
 
 function ReplaceAmpersandsWithUnderscores(const S: string): string; inline;
 begin
-  Result := StringReplace(S, '&', '_', [rfReplaceAll]);
+  Result := StringReplace(S, '_', '__', [rfReplaceAll]);
+  Result := StringReplace(Result, '&', '_', [rfReplaceAll]);
 end;
 
 {-------------------------------------------------------------------------------