diff --git a/src/tempus/Tempus.py b/src/tempus/Tempus.py
index 6e864048def74ede63f554e6b3b5cd6e019679ac..da9ba472e4b1fd729207f1f54df97fb48cce8e1f 100644
--- a/src/tempus/Tempus.py
+++ b/src/tempus/Tempus.py
@@ -19,7 +19,7 @@ from psutil import net_io_counters
 
 from karabo.middlelayer import (
     AccessMode, Bool, Configurable, Device, Double, MetricPrefix, Node, Slot,
-    State, String, UInt16, UInt64, Unit, background, get_property, isSet,
+    State, String, UInt16, UInt64, Unit, background, get_property,
     set_property, sleep)
 
 from ._version import version as deviceVersion
@@ -166,13 +166,13 @@ class Tempus(Device):
     @Slot(
         displayedName="Initialize",
         description="Run the initialization sequence. This will take about "
-                    "45 s.",
+                    "40 s.",
         allowedStates={State.INIT, State.ON})
     async def initialize(self):
         self.state = State.CHANGING
         self.status = "Initializing TEMPUS"
         self.commandLog = (
-            "Initializing TEMPUS:\nThis will take about 45 s.\n\n")
+            "Initializing TEMPUS:\nThis will take about 40 s.\n\n")
         self.background_task = background(self._initialize())
 
     async def _initialize(self):
@@ -363,7 +363,7 @@ class Tempus(Device):
         allowedStates={State.INIT, State.ON})
     async def equalisationFile(self, value):
         self.equalisationFile = value
-        if isSet(value):
+        if self.state not in (State.UNKNOWN, State.ERROR):
             self.state = State.INIT  # force re-initialization
 
     @String(
@@ -372,7 +372,7 @@ class Tempus(Device):
         allowedStates={State.INIT, State.ON})
     async def maskFile(self, value):
         self.maskFile = value
-        if isSet(value):
+        if self.state not in (State.UNKNOWN, State.ERROR):
             self.state = State.INIT  # force re-initialization
 
     externalSync = Bool(
@@ -418,7 +418,6 @@ class Tempus(Device):
             await self.send_command(
                 "mytpx4 = Timepix4control(1)", sleep_time=5)
 
-            self.state = State.INIT
         except Exception as e:
             self.client = None
             self.channel = None