diff --git a/src/function_imaging.pas b/src/function_imaging.pas
index 4a0a454..1c08893 100644
--- a/src/function_imaging.pas
+++ b/src/function_imaging.pas
@@ -55,6 +55,9 @@ begin
   fname := '{f}_(z={z},cx={cx},cy={cy},WxH={w}x{h}).bmp';
   
   fn := stringReplace(args.f, ' ', '', [rfReplaceAll]);
+  fn := stringReplace(fn, '*', '', [rfReplaceAll]);
+  fn := stringReplace(fn, '/', ' div ', [rfReplaceAll]);
+  
   fname := StringReplace(fname, '{f}', fn, []);
   fname := StringReplace(fname, '{z}', floatToStr(args.zoom), []);
   fname := StringReplace(fname, '{cx}', floatToStr(args.centerX), []);