diff --git a/tcl/drivers/ccu4flow.tcl b/tcl/drivers/ccu4flow.tcl
index cf6c0ca..ef0bbfe 100644
--- a/tcl/drivers/ccu4flow.tcl
+++ b/tcl/drivers/ccu4flow.tcl
@@ -546,7 +546,7 @@ proc ccu4flow::ctrl {} {
       } elseif {$now < $lastim + $period} {
         # wait
       } else {
-        set slope [expr 0.01 + abs($dif) * $period / [hvali [sct]/ctrl/deriv$_dir]]
+        set slope [expr 0.00 + abs($dif) * $period / [hvali [sct]/ctrl/deriv$_dir]]
         set totalmin ""
         set ddif [format %.2f [expr -($dif - [sct olddif]) * [sct dir]]]
         sct filtered_ddif [expr max(0,[silent 0 sct filtered_ddif] * 0.9 + $ddif * 0.1)]