diff --git a/src/strings.cpp b/src/strings.cpp
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -1203,9 +1203,9 @@ static char *FormatString(char *buff, co
 			case SCC_CARGO_LONG: { // {CARGO_LONG}
 				/* First parameter is cargo type, second parameter is cargo count */
 				CargoID cargo = args->GetInt32(SCC_CARGO_LONG);
-				if (cargo != CT_INVALID && cargo >= CargoSpec::GetArraySize()) break;
+				if (IsValidCargoID(cargo) && cargo >= CargoSpec::GetArraySize()) break;
 
-				StringID cargo_str = (cargo == CT_INVALID) ? STR_QUANTITY_N_A : CargoSpec::Get(cargo)->quantifier;
+				StringID cargo_str = !IsValidCargoID(cargo) ? STR_QUANTITY_N_A : CargoSpec::Get(cargo)->quantifier;
 				StringParameters tmp_args(*args, 1);
 				buff = GetStringWithArgs(buff, cargo_str, &tmp_args, last);
 				break;