diff --git a/DisplayCAL/wxTestchartEditor.py b/DisplayCAL/wxTestchartEditor.py
index e9b14696..b449ee05 100644
--- a/DisplayCAL/wxTestchartEditor.py
+++ b/DisplayCAL/wxTestchartEditor.py
@@ -2434,7 +2434,7 @@ def tc_multi_bcc_cb_handler(self, event=None):
     def tc_precond_handler(self, event=None):
         setcfg("tc_precond", int(self.tc_precond.GetValue()))
         self.tc_adaption_slider.SetValue(
-            (1 if getcfg("tc_precond") else defaults["tc_adaption"]) * 100
+            int((1 if getcfg("tc_precond") else defaults["tc_adaption"]) * 100)
         )
         self.tc_adaption_handler(self.tc_adaption_slider)
         self.tc_algo_handler()