Index: binaries/data/mods/public/simulation/helpers/Commands.js
===================================================================
--- binaries/data/mods/public/simulation/helpers/Commands.js
+++ binaries/data/mods/public/simulation/helpers/Commands.js
@@ -1124,6 +1124,7 @@
 	// To calculate this with an entity requires ownership, so use the template instead
 	let cmpCost = Engine.QueryInterface(ent, IID_Cost);
 	let costs = cmpCost.GetResourceCosts(player);
+	let popCost = cmpCost.GetPopCost(player);
 
 	if (!cmpPlayer.TrySubtractResources(costs))
 	{
@@ -1134,6 +1135,17 @@
 		cmpPosition.MoveOutOfWorld();
 		return false;
 	}
+	
+	// check pop cost too. Offset the popCost as the entity is added already. Also, notice TryReservePopulationCost can't be used here.
+	if (popCost > (cmpPlayer.GetPopulationLimit() - cmpPlayer.GetPopulationCount() + popCost))
+	{
+		if (g_DebugCommands)
+			warn("Invalid command: building poulation cost check failed for player "+player+": "+uneval(cmd));
+
+		Engine.DestroyEntity(ent);
+		cmpPosition.MoveOutOfWorld();
+		return false;
+	}
 
 	var cmpVisual = Engine.QueryInterface(ent, IID_Visual);
 	if (cmpVisual && cmd.actorSeed !== undefined)