diff --git a/core/src/com/unciv/logic/map/TileInfo.kt b/core/src/com/unciv/logic/map/TileInfo.kt
index f56164ca99..e1f373e31e 100644
--- a/core/src/com/unciv/logic/map/TileInfo.kt
+++ b/core/src/com/unciv/logic/map/TileInfo.kt
@@ -750,7 +750,8 @@ open class TileInfo {
             out.add("Terrain feature [$terrainFeature] does not exist in ruleset!")
         if (resource != null && !ruleset.tileResources.containsKey(resource))
             out.add("Resource [$resource] does not exist in ruleset!")
-        if (improvement != null && !ruleset.tileImprovements.containsKey(improvement))
+        if (improvement != null && !improvement!!.startsWith(TileMap.startingLocationPrefix)
+            && !ruleset.tileImprovements.containsKey(improvement))
             out.add("Improvement [$improvement] does not exist in ruleset!")
         return out
     }
diff --git a/core/src/com/unciv/logic/map/TileMap.kt b/core/src/com/unciv/logic/map/TileMap.kt
index a66142b788..ea9337f461 100644
--- a/core/src/com/unciv/logic/map/TileMap.kt
+++ b/core/src/com/unciv/logic/map/TileMap.kt
@@ -374,11 +374,17 @@ class TileMap {
      *  Is run before setTransients, so make do without startingLocationsByNation
      */
     fun getRulesetIncompatibility(ruleset: Ruleset): HashSet<String> {
-        setTransients(ruleset)
-        setStartingLocationsTransients()
         val rulesetIncompatibilities = HashSet<String>()
         for (set in values.map { it.getRulesetIncompatibility(ruleset) })
             rulesetIncompatibilities.addAll(set)
+
+        // All the rest is to find missing nations
+        try { // This can fail if the map contains a resource that isn't in the ruleset, in TileInfo.tileResource
+            setTransients(ruleset)
+        } catch (ex: Exception) {
+            return rulesetIncompatibilities
+        }
+        setStartingLocationsTransients()
         for ((_, nationName) in startingLocations) {
             if (nationName !in ruleset.nations)
                 rulesetIncompatibilities.add("Nation [$nationName] does not exist in ruleset!")