--- a/include/relpipe/writer/typedefs.h	Tue Dec 10 19:37:43 2019 +0100
+++ b/include/relpipe/writer/typedefs.h	Fri Dec 13 22:19:39 2019 +0100
@@ -26,7 +26,7 @@
 namespace writer {
 
 using octet_t = uint8_t;
-using integer_t = uint64_t;
+using integer_t = int64_t;
 using boolean_t = bool;
 using string_t = std::wstring;
 

--- a/src/types/IntegerDataTypeWriter.h	Tue Dec 10 19:37:43 2019 +0100
+++ b/src/types/IntegerDataTypeWriter.h	Fri Dec 13 22:19:39 2019 +0100
@@ -36,8 +36,8 @@
 using namespace relpipe::writer;
 
 /**
- * Unsigned variable-length integer.
- * ULEB128
+ * Signed variable-length integer.
+ * LEB128
  */
 class IntegerDataTypeWriter : public DataTypeWriter<integer_t> {
 public:
@@ -47,17 +47,19 @@
 
 	void writeValue(std::ostream &output, const integer_t &value) override {
 		integer_t v = value;
+		bool more;
 		do {
 			octet_t octet = v & 0x7F;
 			v >>= 7;
-			if (v) octet |= 0x80; // more bytes follow
+			more = !(((v == 0) && ((octet & 0x40) == 0)) || ((v == -1) && ((octet & 0x40) != 0)));
+			if (more) octet |= 0x80; // more bytes follow
 			output << char(octet);
-		} while (v);
+		} while (more);
 	}
 
 	integer_t toValue(const string_t &stringValue) override {
 		// throws „terminate called after throwing an instance of 'std::invalid_argument'“ SIGABRT, core dumped on invalid number
-		return stoul(stringValue);
+		return stol(stringValue);
 	}
 
 };

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/types/UnsignedIntegerDataTypeWriter.h	Fri Dec 13 22:19:39 2019 +0100
@@ -0,0 +1,67 @@
+/**
+ * Relational pipes (library)
+ * Copyright © 2018 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the:
+ *  - GNU Lesser General Public License as published by the Free Software Foundation;
+ *    version 3 of the License or (at your option)
+ *  - GNU General Public License as published by the Free Software Foundation;
+ *    version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <string>
+#include <iostream>
+#include <cassert>
+#include <limits>
+
+#include <relpipe/protocol/constants.h>
+
+#include "../DataTypeWriter.h"
+
+namespace relpipe {
+namespace writer {
+namespace types {
+
+using namespace relpipe::protocol;
+using namespace relpipe::writer;
+
+/**
+ * Unsigned variable-length integer.
+ * ULEB128
+ */
+class IntegerDataTypeWriter : public DataTypeWriter<integer_t> { // FIXME: relpipe::common::type::UnsignedInteger
+public:
+
+	IntegerDataTypeWriter() : DataTypeWriter<integer_t>(TypeId::INTEGER, DATA_TYPE_CODE_INTEGER) {
+	}
+
+	void writeValue(std::ostream &output, const integer_t &value) override {
+		integer_t v = value;
+		do {
+			octet_t octet = v & 0x7F;
+			v >>= 7;
+			if (v) octet |= 0x80; // more bytes follow
+			output << char(octet);
+		} while (v);
+	}
+
+	integer_t toValue(const string_t &stringValue) override {
+		// throws „terminate called after throwing an instance of 'std::invalid_argument'“ SIGABRT, core dumped on invalid number
+		return stoul(stringValue);
+	}
+
+};
+
+}
+}
+}