diff --git a/fhem/www/pgm2/fhemweb.js b/fhem/www/pgm2/fhemweb.js
index 9c7e71d11..9a18d621b 100644
--- a/fhem/www/pgm2/fhemweb.js
+++ b/fhem/www/pgm2/fhemweb.js
@@ -56,6 +56,7 @@ Slider(slider, min, stp, max, curr, cmd)
 {
   var sh = slider.firstChild;
   var lastX=-1, offX=0, maxX=0, val=-1;
+  min = parseInt(min); max = parseInt(max); stp = parseInt(stp);
 
   function
   init()