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
@@ -1125,7 +1125,8 @@
 	let cmpCost = Engine.QueryInterface(ent, IID_Cost);
 	let costs = cmpCost.GetResourceCosts(player);
 
-	if (!cmpPlayer.TrySubtractResources(costs))
+	// GetPopulationCount already includes the building population
+	if (cmpPlayer.GetPopulationLimit() < cmpPlayer.GetPopulationCount() || !cmpPlayer.TrySubtractResources(costs))
 	{
 		if (g_DebugCommands)
 			warn("Invalid command: building cost check failed for player "+player+": "+uneval(cmd));