diff --git a/core/src/com/unciv/logic/map/MapUnit.kt b/core/src/com/unciv/logic/map/MapUnit.kt
index 0b31ee359e..dbd711c93a 100644
--- a/core/src/com/unciv/logic/map/MapUnit.kt
+++ b/core/src/com/unciv/logic/map/MapUnit.kt
@@ -227,7 +227,8 @@ class MapUnit {
         var unit = baseUnit()
 
         // Go up the upgrade tree until you find the last one which is buildable
-        while (unit.upgradesTo!=null && civInfo.tech.isResearched(unit.getDirectUpgradeUnit(civInfo).requiredTech!!))
+        while (unit.upgradesTo!=null && unit.getDirectUpgradeUnit(civInfo).requiredTech
+                        .let { it==null || civInfo.tech.isResearched(it) })
             unit = unit.getDirectUpgradeUnit(civInfo)
         return unit
     }
diff --git a/core/src/com/unciv/models/ruleset/Ruleset.kt b/core/src/com/unciv/models/ruleset/Ruleset.kt
index 3e93d2b069..253d67fd31 100644
--- a/core/src/com/unciv/models/ruleset/Ruleset.kt
+++ b/core/src/com/unciv/models/ruleset/Ruleset.kt
@@ -250,8 +250,7 @@ class Ruleset {
             for (promotion in unit.promotions)
                 if (!unitPromotions.containsKey(promotion))
                     lines += "${unit.replaces} contains promotion $promotion which does not exist!"
-            if (unit.upgradesTo != null && units.containsKey(unit.upgradesTo!!) && units[unit.upgradesTo!!]!!.requiredTech == null)
-                lines += "${unit.name} upgrades to ${unit.upgradesTo} which has no required tech!"
+
         }
 
         for (building in buildings.values) {