diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0784349..79c5fc9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,10 +5,11 @@ cmake_minimum_required(VERSION 3.12.4)
 option(BUILD_TESTS "Build tests" OFF)
 option(BUILD_UTILS "Build utilities" ON)
 option(BUILD_DOCS "Build documentation" ON)
+option(FORCE_QT5 "Ignore Qt6 when found." OFF)
 
 # Version
 if (NOT PROJECT_VERSION)
-    set(PROJECT_VERSION "0.0.1")
+    set(PROJECT_VERSION "0.1.0")
 endif()
 
 if (NOT PROJECT_VERSION_MAJOR)
@@ -20,7 +21,7 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 # Instruct CMake to run moc automatically when needed
 set(CMAKE_AUTOMOC ON)
 set(CMAKE_CXX_FLAGS "-g -Wall")
-set(QT_MINIMUM_VERSION "5.6.3")
+set(QT5_MINIMUM_VERSION "5.15.0")
 
 # Install settings
 if (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
@@ -29,8 +30,22 @@ endif ()
 
 include(GNUInstallDirs)
 
-# Find the QtWidgets library
-find_package(Qt5 ${QT_MINIMUM_VERSION} CONFIG REQUIRED Core)
+# Find the Qt library
+if (NOT FORCE_QT5)
+  find_package(Qt6 COMPONENTS Core)
+endif()
+if(Qt6_FOUND)
+  message(STATUS "Using Qt6")
+else()
+  find_package(Qt5 ${QT5_MINIMUM_VERSION} COMPONENTS Core)
+  if(Qt5_FOUND)
+    message(STATUS "Using Qt5")
+  endif()
+endif()
+if(NOT Qt${QT_DEFAULT_MAJOR_VERSION}_FOUND)
+  message(FATAL_ERROR "Qt6 or Qt5 >= ${QT5_MINIMUM_VERSION} are required.")
+endif()
+
 find_package(PkgConfig REQUIRED)
 find_package(Doxygen)
 
@@ -39,7 +54,7 @@ pkg_check_modules(GIOMM giomm-2.4) # look into FindPkgConfig.cmake
 add_subdirectory (gio-qt)
 
 if (BUILD_TESTS)
-    find_package(Qt5 ${QT_MINIMUM_VERSION} CONFIG REQUIRED Test)
+    find_package(Qt${QT_DEFAULT_MAJOR_VERSION} COMPONENTS Test REQUIRED)
     add_subdirectory(test)
 endif ()
 
@@ -69,7 +84,7 @@ if (BUILD_DOCS)
         COMMENT "Generate documentation via Doxygen"
     )
 
-    install (FILES ${CMAKE_CURRENT_BINARY_DIR}/docs/gio-qt.qch DESTINATION share/qt5/doc)
+    install (FILES ${CMAKE_CURRENT_BINARY_DIR}/docs/gio-qt.qch DESTINATION share/qt${QT_DEFAULT_MAJOR_VERSION}/doc)
 
 else ()
     message (STATUS "")
diff --git a/gio-qt/CMakeLists.txt b/gio-qt/CMakeLists.txt
index 5805d4f..c7f1bab 100644
--- a/gio-qt/CMakeLists.txt
+++ b/gio-qt/CMakeLists.txt
@@ -55,7 +55,7 @@ PUBLIC
     ${CMAKE_CURRENT_LIST_DIR}/include
 )
 
-target_link_libraries (gio-qt Qt5::Core ${GIOMM_LIBRARIES})
+target_link_libraries (gio-qt Qt::Core ${GIOMM_LIBRARIES})
 
 target_compile_definitions(gio-qt PRIVATE
     QT_NO_KEYWORDS
diff --git a/gio-qt/gio-qt.pc.in b/gio-qt/gio-qt.pc.in
index eb7ebc3..78a812d 100644
--- a/gio-qt/gio-qt.pc.in
+++ b/gio-qt/gio-qt.pc.in
@@ -6,7 +6,7 @@ includedir=${prefix}/include
 Name: gio-qt
 Description: Qt wrapper library for GIO.
 Version: @PROJECT_VERSION@
-Requires: glibmm-2.4, Qt5Core
+Requires: glibmm-2.4, Qt@QT5_MINIMUM_VERSION@Core
 
 Libs: -L${libdir} -lgio-qt
-Cflags: -I${includedir} -I${includedir}/gio-qt
\ No newline at end of file
+Cflags: -I${includedir} -I${includedir}/gio-qt
diff --git a/gio-qt/include/dgiofile.h b/gio-qt/include/dgiofile.h
index 1a39f4a..7f5b71d 100644
--- a/gio-qt/include/dgiofile.h
+++ b/gio-qt/include/dgiofile.h
@@ -8,6 +8,8 @@
 #include <QObject>
 #include <QSharedData>
 
+#include <climits>
+
 namespace Gio {
 class File;
 }
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 20d7b19..d5055c1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -10,7 +10,7 @@ function(DGIO_CREATE_TEST _generated_target_name _input_file_name _use_giomm)
         ${_input_file_name}
     )
     add_test (NAME ${_generated_target_name} COMMAND ${_generated_target_name} )
-    target_link_libraries (${_generated_target_name} gio-qt Qt5::Test ${extra_libraries})
+    target_link_libraries (${_generated_target_name} gio-qt Qt::Test ${extra_libraries})
     if (_use_giomm)
         target_include_directories(${_generated_target_name} PRIVATE ${GIOMM_INCLUDE_DIRS})
         target_compile_definitions(${_generated_target_name} PRIVATE QT_NO_KEYWORDS)