diff --git a/code/classes/SCDsignal_isvalid.m b/code/classes/SCDsignal_isvalid.m
index fba6baf8835bbfe8c57d6726b3600bf5e19120da..499a0787311539b3a3ffca407093f269c387682d 100644
--- a/code/classes/SCDsignal_isvalid.m
+++ b/code/classes/SCDsignal_isvalid.m
@@ -4,8 +4,8 @@ function isvalid = SCDsignal_isvalid(SCDsignals)
 isvalid = false(size(SCDsignals));
 
 for ii=1:numel(SCDsignals)
-  isRunning = strcmp(char(SCDsignals(ii).ProductionState) , 'RUNNING');
-  isGood    = strcmp(char(SCDsignals(ii).QualityTag)      ,    'GOOD');
+  isRunning = int8(SCDsignals(ii).ProductionState) == int8(ProductionState.RUNNING);
+  isGood    = int8(SCDsignals(ii).QualityTag)      == int8(QualityTag.GOOD);
   isvalid(ii) = isRunning & isGood;
 end
 end
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