diff --git a/core/src/com/unciv/models/ruleset/unique/UniqueTriggerActivation.kt b/core/src/com/unciv/models/ruleset/unique/UniqueTriggerActivation.kt
index daca4ce95c..4a34d33924 100644
--- a/core/src/com/unciv/models/ruleset/unique/UniqueTriggerActivation.kt
+++ b/core/src/com/unciv/models/ruleset/unique/UniqueTriggerActivation.kt
@@ -380,7 +380,7 @@ object UniqueTriggerActivation {
 
             UniqueType.OneTimeGainPopulation -> {
                 val applicableCities =
-                    if (unique.params[1] == "in this city") sequenceOf(relevantCity!!)
+                    if (unique.params[1] == "in this city") sequenceOf(relevantCity).filterNotNull()
                     else civInfo.cities.asSequence().filter { it.matchesFilter(unique.params[1]) }
                 if (applicableCities.none()) return null
                 return {