diff --git a/src/main/scala/edu/ie3/simona/agent/participant/hp/HpAgentFundamentals.scala b/src/main/scala/edu/ie3/simona/agent/participant/hp/HpAgentFundamentals.scala
index fa7281857d..5e55c467a0 100644
--- a/src/main/scala/edu/ie3/simona/agent/participant/hp/HpAgentFundamentals.scala
+++ b/src/main/scala/edu/ie3/simona/agent/participant/hp/HpAgentFundamentals.scala
@@ -272,7 +272,7 @@ trait HpAgentFundamentals
           baseStateData.copy(
             stateDataStore = updatedStateDataStore,
             additionalActivationTicks =
-              baseStateData.additionalActivationTicks + nextThreshold.tick,
+              baseStateData.additionalActivationTicks ++ Set(nextThreshold.tick),
           )
         case _ =>
           baseStateData.copy(