--- a/src/ArgumentsCommand.h	Wed Oct 30 16:47:41 2019 +0100
+++ b/src/ArgumentsCommand.h	Fri Dec 13 22:19:38 2019 +0100
@@ -39,7 +39,7 @@
 
 		size_t i = 0;
 		string_t relationName = arguments[i++];
-		integer_t attributeCount = std::stoul(arguments[i++]); // TODO: use integer data type's method?
+		integer_t attributeCount = std::stol(arguments[i++]); // TODO: use integer data type's method? + unsigned type
 		boolean_t writeHeader = true; // TODO: add option for header omitting
 
 		// TODO: check argument count

--- a/src/StdInCommand.h	Wed Oct 30 16:47:41 2019 +0100
+++ b/src/StdInCommand.h	Fri Dec 13 22:19:38 2019 +0100
@@ -88,7 +88,7 @@
 
 		size_t i = 0;
 		string_t relationName = readNext(input, arguments, i, true);
-		integer_t attributeCount = std::stoul(readNext(input, arguments, i, true)); // TODO: use integer data type's method?
+		integer_t attributeCount = std::stol(readNext(input, arguments, i, true)); // TODO: use integer data type's method? + unsigned type
 		boolean_t writeHeader = true; // TODO: add option for header omitting
 
 		std::shared_ptr<RelationalWriter> writer(Factory::create(output));