diff --git a/src/economy.cpp b/src/economy.cpp
index a9a61850d2..dcf7d39903 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -1517,8 +1517,12 @@ CommandCost CmdBuyShareInCompany(TileIndex tile, DoCommandFlag flags, uint32 p1,
 	/* Those lines are here for network-protection (clients can be slow) */
 	if (GetAmountOwnedBy(c, COMPANY_SPECTATOR) == 0) return cost;
 
-	/* We can not buy out a real company (temporarily). TODO: well, enable it obviously */
-	if (GetAmountOwnedBy(c, COMPANY_SPECTATOR) == 1 && !c->is_ai) return cost;
+	if (GetAmountOwnedBy(c, COMPANY_SPECTATOR) == 1) {
+		if (!c->is_ai) return cost; //  We can not buy out a real company (temporarily). TODO: well, enable it obviously.
+
+		if (GetAmountOwnedBy(c, _current_company) == 3 && !MayCompanyTakeOver(_current_company, target_company)) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
+	}
+
 
 	cost.AddCost(CalculateCompanyValue(c) >> 2);
 	if (flags & DC_EXEC) {