diff --git a/CMakeLists.txt b/CMakeLists.txt
index cd1d4d7..6bc9a2d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,38 +9,53 @@ set(CMAKE_C_VISIBILITY_PRESET hidden)
 set(CMAKE_CXX_VISIBILITY_PRESET hidden)
 
 option(BUILD_SHARED_LIBS "Build using shared libraries" ON)
+option(USE_BUNDLED_LIBS "Use bundled LZ4 PugiXML and Zlib" ON)
+
+if(USE_BUNDLED_LIBS)
+set(THIRD_PARTY_SRC
+    lz4/lz4.c
+    lz4/lz4.h
+    lz4/lz4hc.c
+    lz4/lz4hc.h
+    pugixml/pugixml.cpp
+    zlib/adler32.c
+    zlib/compress.c
+    zlib/crc32.c
+    zlib/deflate.c
+    zlib/gzclose.c
+    zlib/gzlib.c
+    zlib/gzread.c
+    zlib/gzwrite.c
+    zlib/inflate.c
+    zlib/infback.c
+    zlib/inftrees.c
+    zlib/inffast.c
+    zlib/trees.c
+    zlib/uncompr.c
+    zlib/zutil.c)
+else(USE_BUNDLED_LIBS)
+    find_package(PkgConfig REQUIRED)
+    pkg_check_modules(LZ4 liblz4 IMPORTED_TARGET REQUIRED)
+    pkg_check_modules(PUGIXML pugixml IMPORTED_TARGET REQUIRED)
+    pkg_check_modules(ZLIB zlib IMPORTED_TARGET REQUIRED)
+endif(USE_BUNDLED_LIBS)
 
 add_library(XISF
   bytearray.cpp
-  bytearray.h
   libXISF_global.h
   libxisf.cpp
   libxisf.h
   utils.cpp
   variant.cpp
-  variant.h
-  lz4/lz4.c
-  lz4/lz4.h
-  lz4/lz4hc.c
-  lz4/lz4hc.h
-  pugixml/pugixml.cpp
-  zlib/adler32.c
-  zlib/compress.c
-  zlib/crc32.c
-  zlib/deflate.c
-  zlib/gzclose.c
-  zlib/gzlib.c
-  zlib/gzread.c
-  zlib/gzwrite.c
-  zlib/inflate.c
-  zlib/infback.c
-  zlib/inftrees.c
-  zlib/inffast.c
-  zlib/trees.c
-  zlib/uncompr.c
-  zlib/zutil.c
+  ${THIRD_PARTY_SRC}
 )
 
+if(USE_BUNDLED_LIBS)
+    target_include_directories(XISF PRIVATE lz4 pugixml zlib)
+else(USE_BUNDLED_LIBS)
+    target_link_libraries(XISF PUBLIC PkgConfig::LZ4 PkgConfig::PUGIXML PkgConfig::ZLIB)
+endif(USE_BUNDLED_LIBS)
+
 set_target_properties(XISF PROPERTIES VERSION ${PROJECT_VERSION} SOVERSION ${PROJECT_VERSION_MAJOR})
 
 if(BUILD_SHARED_LIBS)
diff --git a/bytearray.h b/bytearray.h
deleted file mode 100644
index 92bfb50..0000000
--- a/bytearray.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/************************************************************************
- * LibXISF - library to load and save XISF files                        *
- * Copyright (C) 2023 Dušan Poizl                                       *
- *                                                                      *
- * This program is free software: you can redistribute it and/or modify *
- * it under the terms of the GNU General Public License as published by *
- * the Free Software Foundation, either version 3 of the License, or    *
- * (at your option) any later version.                                  *
- *                                                                      *
- * 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/>.*
- ************************************************************************/
-
-#ifndef LIBXISF_BYTEARRAY_H
-#define LIBXISF_BYTEARRAY_H
-
-namespace LibXISF
-{
-
-
-
-}
-
-#endif // LIBXISF_BYTEARRAY_H
diff --git a/libxisf.cpp b/libxisf.cpp
index d35ef03..660e7f5 100644
--- a/libxisf.cpp
+++ b/libxisf.cpp
@@ -23,10 +23,10 @@
 #include <iostream>
 #include <sstream>
 #include <cstdlib>
-#include "lz4/lz4.h"
-#include "lz4/lz4hc.h"
-#include "pugixml/pugixml.hpp"
-#include "zlib/zlib.h"
+#include <lz4.h>
+#include <lz4hc.h>
+#include <pugixml.hpp>
+#include <zlib.h>
 
 namespace LibXISF
 {
diff --git a/libxisf.h b/libxisf.h
index 5dae177..2587299 100644
--- a/libxisf.h
+++ b/libxisf.h
@@ -25,7 +25,10 @@
 #include <variant>
 #include <fstream>
 #include <cstring>
-#include "variant.h"
+#include <vector>
+#include <cstdint>
+#include <memory>
+#include <ctime>
 
 namespace LibXISF
 {
@@ -64,6 +67,103 @@ public:
     void decodeHex();
 };
 
+struct Complex32
+{
+    float real;
+    float imag;
+};
+
+struct Complex64
+{
+    double real;
+    double imag;
+};
+
+template<typename T>
+class Matrix
+{
+    int _rows = 0;
+    int _cols = 0;
+    std::vector<T> _elem;
+public:
+    using value_type = T;
+
+    Matrix() = default;
+    Matrix(int rows, int cols) : _rows(rows), _cols(cols), _elem(rows * cols) {}
+    void resize(int rows, int cols) { _rows = rows; _cols = cols; _elem.resize(rows * cols); }
+    T& operator()(int row, int col) { return _elem[row * _cols + col]; }
+    const T& operator()(int row, int col) const { return _elem[row * _cols + col]; }
+    int rows() const { return _rows; }
+    int cols() const { return _cols; }
+};
+
+typedef bool Boolean;
+typedef int8_t Int8;
+typedef uint8_t UInt8;
+typedef int16_t Int16;
+typedef uint16_t UInt16;
+typedef int32_t Int32;
+typedef uint32_t UInt32;
+typedef int64_t Int64;
+typedef uint64_t UInt64;
+typedef float Float32;
+typedef double Float64;
+typedef std::string String;
+typedef std::tm TimePoint;
+typedef std::vector<int8_t> I8Vector;
+typedef std::vector<uint8_t> UI8Vector;
+typedef std::vector<int16_t> I16Vector;
+typedef std::vector<uint16_t> UI16Vector;
+typedef std::vector<int32_t> I32Vector;
+typedef std::vector<uint32_t> UI32Vector;
+typedef std::vector<int64_t> I64Vector;
+typedef std::vector<uint64_t> UI64Vector;
+typedef std::vector<float> F32Vector;
+typedef std::vector<double> F64Vector;
+typedef std::vector<Complex32> C32Vector;
+typedef std::vector<Complex64> C64Vector;
+typedef Matrix<Int8> I8Matrix;
+typedef Matrix<UInt8> UI8Matrix;
+typedef Matrix<Int16> I16Matrix;
+typedef Matrix<UInt16> UI16Matrix;
+typedef Matrix<Int32> I32Matrix;
+typedef Matrix<UInt32> UI32Matrix;
+typedef Matrix<Int64> I64Matrix;
+typedef Matrix<UInt64> UI64Matrix;
+typedef Matrix<float> F32Matrix;
+typedef Matrix<double> F64Matrix;
+typedef Matrix<Complex32> C32Matrix;
+typedef Matrix<Complex64> C64Matrix;
+
+class Variant
+{
+    using StdVariant = std::variant<std::monostate, Boolean, Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64, Float32, Float64,
+        Complex32, Complex64, String, TimePoint,
+        I8Vector, UI8Vector, I16Vector, UI16Vector, I32Vector, UI32Vector, I64Vector, UI64Vector, F32Vector, F64Vector, C32Vector, C64Vector,
+        I8Matrix, UI8Matrix, I16Matrix, UI16Matrix, I32Matrix, UI32Matrix, I64Matrix, UI64Matrix, F32Matrix, F64Matrix, C32Matrix, C64Matrix>;
+    StdVariant _value;
+public:
+    enum class Type
+    {
+        Monostate, Boolean, Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64, Float32, Float64,
+        Complex32, Complex64, String, TimePoint,
+        I8Vector, UI8Vector, I16Vector, UI16Vector, I32Vector, UI32Vector, I64Vector, UI64Vector, F32Vector, F64Vector, C32Vector, C64Vector,
+        I8Matrix, UI8Matrix, I16Matrix, UI16Matrix, I32Matrix, UI32Matrix, I64Matrix, UI64Matrix, F32Matrix, F64Matrix, C32Matrix, C64Matrix
+    };
+
+    Variant() = default;
+    template<typename T>
+    Variant(const T &t) : _value(t) {}
+    Type type() const;
+    const char *typeName() const;
+    template<typename T>
+    T& value() { return std::get<T>(_value); }
+    template<typename T>
+    const T& value() const { return std::get<T>(_value); }
+    template<typename T>
+    void setValue(const T& val) { _value = val; }
+};
+
 struct LIBXISF_EXPORT DataBlock
 {
     enum CompressionCodec
diff --git a/variant.cpp b/variant.cpp
index 9a3b967..215abbb 100644
--- a/variant.cpp
+++ b/variant.cpp
@@ -16,7 +16,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.*
  ************************************************************************/
 
-#include "variant.h"
 #include <charconv>
 #include <type_traits>
 #include <map>
@@ -336,7 +335,7 @@ void serializeVariant(pugi::xml_node &node, const Variant &variant)
         }
         node.append_attribute("length").set_value(len);
         node.append_attribute("location").set_value("inline:base64");
-        node.append_child(pugi::node_pcdata).set_value(data.constData(), data.size());
+        node.append_child(pugi::node_pcdata).set_value(data.constData());
     }
     else if(variant.type() >= Variant::Type::I8Matrix && variant.type() <= Variant::Type::C64Matrix)
     {
@@ -363,7 +362,7 @@ void serializeVariant(pugi::xml_node &node, const Variant &variant)
         node.append_attribute("rows").set_value(rows);
         node.append_attribute("columns").set_value(cols);
         node.append_attribute("location").set_value("inline:base64");
-        node.append_child(pugi::node_pcdata).set_value(data.constData(), data.size());
+        node.append_child(pugi::node_pcdata).set_value(data.constData());
     }
     else if(variant.type() == Variant::Type::TimePoint)
     {
diff --git a/variant.h b/variant.h
deleted file mode 100644
index 19993fd..0000000
--- a/variant.h
+++ /dev/null
@@ -1,134 +0,0 @@
-/************************************************************************
- * LibXISF - library to load and save XISF files                        *
- * Copyright (C) 2023 Dušan Poizl                                       *
- *                                                                      *
- * This program is free software: you can redistribute it and/or modify *
- * it under the terms of the GNU General Public License as published by *
- * the Free Software Foundation, either version 3 of the License, or    *
- * (at your option) any later version.                                  *
- *                                                                      *
- * 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/>.*
- ************************************************************************/
-
-#ifndef LIBXISF_VARIANT_H
-#define LIBXISF_VARIANT_H
-
-#include <variant>
-#include <cstdint>
-#include <string>
-#include <vector>
-#include <memory>
-#include <cstring>
-#include <ctime>
-#include <sstream>
-#include "libXISF_global.h"
-
-namespace LibXISF
-{
-
-struct Complex32
-{
-    float real;
-    float imag;
-};
-
-struct Complex64
-{
-    double real;
-    double imag;
-};
-
-template<typename T>
-class Matrix
-{
-    int _rows = 0;
-    int _cols = 0;
-    std::vector<T> _elem;
-public:
-    using value_type = T;
-
-    Matrix() = default;
-    Matrix(int rows, int cols) : _rows(rows), _cols(cols), _elem(rows * cols) {}
-    void resize(int rows, int cols) { _rows = rows; _cols = cols; _elem.resize(rows * cols); }
-    T& operator()(int row, int col) { return _elem[row * _cols + col]; }
-    const T& operator()(int row, int col) const { return _elem[row * _cols + col]; }
-    int rows() const { return _rows; }
-    int cols() const { return _cols; }
-};
-
-typedef bool Boolean;
-typedef int8_t Int8;
-typedef uint8_t UInt8;
-typedef int16_t Int16;
-typedef uint16_t UInt16;
-typedef int32_t Int32;
-typedef uint32_t UInt32;
-typedef int64_t Int64;
-typedef uint64_t UInt64;
-typedef float Float32;
-typedef double Float64;
-typedef std::string String;
-typedef std::tm TimePoint;
-typedef std::vector<int8_t> I8Vector;
-typedef std::vector<uint8_t> UI8Vector;
-typedef std::vector<int16_t> I16Vector;
-typedef std::vector<uint16_t> UI16Vector;
-typedef std::vector<int32_t> I32Vector;
-typedef std::vector<uint32_t> UI32Vector;
-typedef std::vector<int64_t> I64Vector;
-typedef std::vector<uint64_t> UI64Vector;
-typedef std::vector<float> F32Vector;
-typedef std::vector<double> F64Vector;
-typedef std::vector<Complex32> C32Vector;
-typedef std::vector<Complex64> C64Vector;
-typedef Matrix<Int8> I8Matrix;
-typedef Matrix<UInt8> UI8Matrix;
-typedef Matrix<Int16> I16Matrix;
-typedef Matrix<UInt16> UI16Matrix;
-typedef Matrix<Int32> I32Matrix;
-typedef Matrix<UInt32> UI32Matrix;
-typedef Matrix<Int64> I64Matrix;
-typedef Matrix<UInt64> UI64Matrix;
-typedef Matrix<float> F32Matrix;
-typedef Matrix<double> F64Matrix;
-typedef Matrix<Complex32> C32Matrix;
-typedef Matrix<Complex64> C64Matrix;
-
-class Variant
-{
-    using StdVariant = std::variant<std::monostate, Boolean, Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64, Float32, Float64,
-        Complex32, Complex64, String, TimePoint,
-        I8Vector, UI8Vector, I16Vector, UI16Vector, I32Vector, UI32Vector, I64Vector, UI64Vector, F32Vector, F64Vector, C32Vector, C64Vector,
-        I8Matrix, UI8Matrix, I16Matrix, UI16Matrix, I32Matrix, UI32Matrix, I64Matrix, UI64Matrix, F32Matrix, F64Matrix, C32Matrix, C64Matrix>;
-    StdVariant _value;
-public:
-    enum class Type
-    {
-        Monostate, Boolean, Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64, Float32, Float64,
-        Complex32, Complex64, String, TimePoint,
-        I8Vector, UI8Vector, I16Vector, UI16Vector, I32Vector, UI32Vector, I64Vector, UI64Vector, F32Vector, F64Vector, C32Vector, C64Vector,
-        I8Matrix, UI8Matrix, I16Matrix, UI16Matrix, I32Matrix, UI32Matrix, I64Matrix, UI64Matrix, F32Matrix, F64Matrix, C32Matrix, C64Matrix
-    };
-
-    Variant() = default;
-    template<typename T>
-    Variant(const T &t) : _value(t) {}
-    Type type() const;
-    const char *typeName() const;
-    template<typename T>
-    T& value() { return std::get<T>(_value); }
-    template<typename T>
-    const T& value() const { return std::get<T>(_value); }
-    template<typename T>
-    void setValue(const T& val) { _value = val; }
-};
-
-}
-
-#endif // LIBXISF_VARIANT_H