diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index bf1ecde..57ed038 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,13 +1,19 @@
-name: 🧪Qt 5 linux build
+name: 🧪 Linux build
 
 on:
   push:
+    branches:
+      - main
   pull_request:
     branches:
       - main
 
 jobs:
   build:
+    strategy:
+      matrix:
+        qt_version: [5, 6]
+
     runs-on: ubuntu-latest
     
     steps:
@@ -16,41 +22,56 @@ jobs:
         
       - name: Get deps
         run: |
+          if [ "${{ matrix.qt_version }}" -eq 6 ]; then
+              QT_PACKAGES="qt6-base-dev \
+                qtkeychain-qt6-dev \
+                qt6-webengine-dev \
+                qt6-webengine-dev-tools \
+                libglx-dev \
+                libgl1-mesa-dev"
+          else
+              QT_PACKAGES="qtbase5-dev \
+                qt5keychain-dev \
+                qtscript5-dev \
+                qtwebengine5-dev"
+          fi
           sudo apt-get install \
             cmake \
             ninja-build \
             clang \
-            qtbase5-dev \
-            qt5keychain-dev \
-            qtscript5-dev \
-            qtwebengine5-dev
+            ${QT_PACKAGES}
+
           
       - name: Build
         run: |
-          mkdir -p build
-          cd build
+          if [ "${{ matrix.qt_version }}" -eq 6 ]; then
+              CMAKE_QT_OPTION="o2_WITH_QT6:BOOL=ON"
+          else
+              CMAKE_QT_OPTION="o2_WITH_QT6:BOOL=OFF"
+          fi
           cmake -GNinja \
-          -Do2_BUILD_EXAMPLES:BOOL=ON \
-          -Do2_WITH_TESTS=ON \
-          -Do2_SHOW_TRACE:BOOL=ON \
-          -Do2_WITH_DROPBOX:BOOL=ON \
-          -Do2_WITH_FACEBOOK:BOOL=ON \
-          -Do2_WITH_FLICKR:BOOL=ON \
-          -Do2_WITH_GOOGLE:BOOL=ON \
-          -Do2_WITH_HUBIC:BOOL=ON \
-          -Do2_WITH_KEYCHAIN:BOOL=ON \
-          -Do2_WITH_MSGRAPH:BOOL=ON \
-          -Do2_WITH_OAUTH1:BOOL=ON \
-          -Do2_WITH_QT5:BOOL=ON \
-          -Do2_WITH_SKYDRIVE:BOOL=ON \
-          -Do2_WITH_SMUGMUG:BOOL=ON \
-          -Do2_WITH_SPOTIFY:BOOL=ON \
-          -Do2_WITH_SURVEYMONKEY:BOOL=ON \
-          -Do2_WITH_TWITTER:BOOL=ON \
-          -Do2_WITH_UBER:BOOL=ON \
-          -Do2_WITH_VIMEO:BOOL=ON \
-          ..
-          ninja
+            -Do2_BUILD_EXAMPLES:BOOL=ON \
+            -Do2_WITH_TESTS=ON \
+            -Do2_SHOW_TRACE:BOOL=ON \
+            -Do2_WITH_DROPBOX:BOOL=ON \
+            -Do2_WITH_FACEBOOK:BOOL=ON \
+            -Do2_WITH_FLICKR:BOOL=ON \
+            -Do2_WITH_GOOGLE:BOOL=ON \
+            -Do2_WITH_HUBIC:BOOL=ON \
+            -Do2_WITH_KEYCHAIN:BOOL=ON \
+            -Do2_WITH_MSGRAPH:BOOL=ON \
+            -Do2_WITH_OAUTH1:BOOL=ON \
+            -D${CMAKE_QT_OPTION} \
+            -Do2_WITH_SKYDRIVE:BOOL=ON \
+            -Do2_WITH_SMUGMUG:BOOL=ON \
+            -Do2_WITH_SPOTIFY:BOOL=ON \
+            -Do2_WITH_SURVEYMONKEY:BOOL=ON \
+            -Do2_WITH_TWITTER:BOOL=ON \
+            -Do2_WITH_UBER:BOOL=ON \
+            -Do2_WITH_VIMEO:BOOL=ON \
+            -S . \
+            -B build
+          cmake --build build
 
       - name: Run Tests
         run: |
diff --git a/.github/workflows/clang_static_analyzer/start.sh b/.github/workflows/clang_static_analyzer/start.sh
index af49bc3..4bbaf59 100755
--- a/.github/workflows/clang_static_analyzer/start.sh
+++ b/.github/workflows/clang_static_analyzer/start.sh
@@ -32,7 +32,7 @@ scan-build -o scanbuildoutput -plist -v cmake -Do2_BUILD_EXAMPLES:BOOL=ON \
     -Do2_WITH_KEYCHAIN:BOOL=ON \
     -Do2_WITH_MSGRAPH:BOOL=ON \
     -Do2_WITH_OAUTH1:BOOL=ON \
-    -Do2_WITH_QT5:BOOL=ON \
+    -Do2_WITH_QT6:BOOL=OFF \
     -Do2_WITH_SKYDRIVE:BOOL=ON \
     -Do2_WITH_SMUGMUG:BOOL=ON \
     -Do2_WITH_SPOTIFY:BOOL=ON \
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 857e3d4..455e1e4 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -98,7 +98,7 @@ jobs:
             -Do2_WITH_KEYCHAIN:BOOL=ON \
             -Do2_WITH_MSGRAPH:BOOL=ON \
             -Do2_WITH_OAUTH1:BOOL=ON \
-            -Do2_WITH_QT5:BOOL=ON \
+            -Do2_WITH_QT6:BOOL=OFF \
             -Do2_WITH_SKYDRIVE:BOOL=ON \
             -Do2_WITH_SMUGMUG:BOOL=ON \
             -Do2_WITH_SPOTIFY:BOOL=ON \
diff --git a/.github/workflows/coverity-scan.yml b/.github/workflows/coverity-scan.yml
index c1d1c5c..e2d5446 100644
--- a/.github/workflows/coverity-scan.yml
+++ b/.github/workflows/coverity-scan.yml
@@ -36,7 +36,7 @@ jobs:
             -Do2_WITH_KEYCHAIN:BOOL=ON \
             -Do2_WITH_MSGRAPH:BOOL=ON \
             -Do2_WITH_OAUTH1:BOOL=ON \
-            -Do2_WITH_QT5:BOOL=ON \
+            -Do2_WITH_QT6:BOOL=OFF \
             -Do2_WITH_SKYDRIVE:BOOL=ON \
             -Do2_WITH_SMUGMUG:BOOL=ON \
             -Do2_WITH_SPOTIFY:BOOL=ON \
diff --git a/.github/workflows/mac/install.sh b/.github/workflows/mac/install.sh
index 5e5acb5..c630c05 100644
--- a/.github/workflows/mac/install.sh
+++ b/.github/workflows/mac/install.sh
@@ -26,7 +26,7 @@ cmake -GNinja \
     -Do2_WITH_KEYCHAIN:BOOL=ON \
     -Do2_WITH_MSGRAPH:BOOL=ON \
     -Do2_WITH_OAUTH1:BOOL=ON \
-    -Do2_WITH_QT5:BOOL=ON \
+    -Do2_WITH_QT6:BOOL=OFF \
     -Do2_WITH_SKYDRIVE:BOOL=ON \
     -Do2_WITH_SMUGMUG:BOOL=ON \
     -Do2_WITH_SPOTIFY:BOOL=ON \
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f0cd666..01fdd05 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,7 +18,7 @@ set(API_VERSION ${VER_MAJOR}.${VER_MINOR}.${API_VER_PATCH})
 
 project(o2 VERSION ${PROJECT_VERSION})
 
-option(o2_WITH_QT5 "Use Qt5" ON)
+option(o2_WITH_QT6 "Use Qt6" ON)
 
 set(o2_LIB_SUFFIX "" CACHE STRING "Suffix for install 'lib' directory, e.g. 64 for lib64")
 
@@ -89,14 +89,11 @@ if (o2_WITH_OAUTH1)
 endif()
 
 if(o2_WITH_KEYCHAIN)
-    if(o2_WITH_QT5)
-        find_package(Qt5Keychain CONFIG REQUIRED)
-    else()
+    if(o2_WITH_QT6)
         find_package(Qt6Keychain CONFIG REQUIRED)
+    else()
+        find_package(Qt5Keychain CONFIG REQUIRED)
     endif()
-
-    message("Found QTKeychain")
-
 endif(o2_WITH_KEYCHAIN)
 
 if(o2_WITH_TWITTER OR o2_WITH_DROPBOX OR o2_WITH_FLICKR OR o2_WITH_SMUGMUG)
diff --git a/examples/facebookdemo/CMakeLists.txt b/examples/facebookdemo/CMakeLists.txt
index 61f4a7a..981866d 100644
--- a/examples/facebookdemo/CMakeLists.txt
+++ b/examples/facebookdemo/CMakeLists.txt
@@ -6,21 +6,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-    find_package(Qt5Script  REQUIRED)
-    find_package(Qt5Network REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -30,15 +20,7 @@ set(fb_SRCS
     fbdemo.h
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( fbexample ${fb_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( fbexample Qt5::Core Qt5::Widgets Qt5::Network )
-    target_link_libraries( fbexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( fbexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( fbexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( fbexample o2 )
diff --git a/examples/facebookexternalinterceptordemo/CMakeLists.txt b/examples/facebookexternalinterceptordemo/CMakeLists.txt
index afc3d27..8614c7c 100644
--- a/examples/facebookexternalinterceptordemo/CMakeLists.txt
+++ b/examples/facebookexternalinterceptordemo/CMakeLists.txt
@@ -6,21 +6,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-    find_package(Qt5Script  REQUIRED)
-    find_package(Qt5Network REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -29,15 +19,7 @@ set(fb_SRCS
     fbdemo.cpp
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( fbexample ${fb_SRCS} )
 
-if(o2_WITH_QT5)
-    qt5_use_modules( fbexample Core Widgets Network )
-    target_link_libraries( fbexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( fbexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( fbexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( fbexample o2 )
diff --git a/examples/msgraphdemo/CMakeLists.txt b/examples/msgraphdemo/CMakeLists.txt
index c131f4a..5fe8bd8 100644
--- a/examples/msgraphdemo/CMakeLists.txt
+++ b/examples/msgraphdemo/CMakeLists.txt
@@ -6,21 +6,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Gui     REQUIRED)
-    find_package(Qt5Network REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -30,15 +20,7 @@ set(msgraph_SRCS
     msgraphdemo.h
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( msgraphexample ${msgraph_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( msgraphexample Qt5::Core Qt5::Gui Qt5::Network Qt5::Widgets )
-    target_link_libraries( msgraphexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( msgraphexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( msgraphexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( msgraphexample o2 )
diff --git a/examples/msgraphexternalinterceptordemo/CMakeLists.txt b/examples/msgraphexternalinterceptordemo/CMakeLists.txt
index 4b4373b..b2ba18b 100644
--- a/examples/msgraphexternalinterceptordemo/CMakeLists.txt
+++ b/examples/msgraphexternalinterceptordemo/CMakeLists.txt
@@ -7,23 +7,11 @@ set(CMAKE_AUTOUIC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-    find_package(Qt5Script  REQUIRED)
-    find_package(Qt5Network REQUIRED)
-    find_package(Qt5WebEngine REQUIRED)
-    find_package(Qt5WebEngineWidgets REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network WebEngineCore WebEngineWidgets REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network WebEngine WebEngineWidgets REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -34,15 +22,7 @@ set(msgraph_SRCS
     webenginepage.cpp
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( msgraphexternalinterceptorexample ${msgraph_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( msgraphexternalinterceptorexample Qt5::Core Qt5::Widgets Qt5::Network Qt5::WebEngine Qt5::WebEngineWidgets )
-    target_link_libraries( msgraphexternalinterceptorexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( msgraphexternalinterceptorexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( msgraphexternalinterceptorexample Qt::Core Qt::Widgets Qt::Network Qt::WebEngineWidgets )
+target_link_libraries( msgraphexternalinterceptorexample o2 )
diff --git a/examples/twitterdemo/CMakeLists.txt b/examples/twitterdemo/CMakeLists.txt
index ac677bd..7eb2d95 100644
--- a/examples/twitterdemo/CMakeLists.txt
+++ b/examples/twitterdemo/CMakeLists.txt
@@ -6,22 +6,12 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-    find_package(Qt5Script  REQUIRED)
-    find_package(Qt5Network REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
- 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
 set(fb_SRCS
@@ -29,15 +19,7 @@ set(fb_SRCS
     tweeter.cpp
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( twitterexample ${fb_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( twitterexample Qt5::Core Qt5::Widgets Qt5::Network )
-    target_link_libraries( twitterexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( twitterexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( twitterexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( twitterexample o2 )
diff --git a/examples/vimeodemo/CMakeLists.txt b/examples/vimeodemo/CMakeLists.txt
index cc417bd..5145d76 100644
--- a/examples/vimeodemo/CMakeLists.txt
+++ b/examples/vimeodemo/CMakeLists.txt
@@ -6,21 +6,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Gui     REQUIRED)
-    find_package(Qt5Network REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -30,15 +20,7 @@ set(vimeo_SRCS
     vimeodemo.h
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( vimeoexample ${vimeo_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( vimeoexample Qt5::Core Qt5::Gui Qt5::Network Qt5::Widgets )
-    target_link_libraries( vimeoexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( vimeoexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( vimeoexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( vimeoexample o2 )
diff --git a/examples/youtubedemo/CMakeLists.txt b/examples/youtubedemo/CMakeLists.txt
index 530d30a..7a0eba0 100644
--- a/examples/youtubedemo/CMakeLists.txt
+++ b/examples/youtubedemo/CMakeLists.txt
@@ -6,21 +6,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
-    # Qt5 packages find their own dependencies.
-    find_package(Qt5Core    REQUIRED)
-    find_package(Qt5Gui     REQUIRED)
-    find_package(Qt5Network REQUIRED)
-    find_package(Qt5Widgets REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Widgets Network REQUIRED)
+else()
+    find_package(Qt5 COMPONENTS Core Widgets Script Network REQUIRED)
+endif()
 
 include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} "../../src" )
 
@@ -30,15 +20,7 @@ set(yt_SRCS
     ytdemo.h
 )
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 add_executable( ytexample ${yt_SRCS} )
 
-if(o2_WITH_QT5)
-    target_link_libraries( ytexample Qt5::Core Qt5::Gui Qt5::Network Qt5::Widgets )
-    target_link_libraries( ytexample o2 )
-else(o2_WITH_QT5)
-    target_link_libraries( ytexample ${QT_LIBRARIES} o2 )
-endif(o2_WITH_QT5)
+target_link_libraries( ytexample Qt::Core Qt::Widgets Qt::Network )
+target_link_libraries( ytexample o2 )
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 323f8c2..7f144bc 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -4,19 +4,11 @@ set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
-if(o2_WITH_QT5)
+if(o2_WITH_QT6)
+    find_package(Qt6 COMPONENTS Core Network REQUIRED)
+else()
     find_package(Qt5 COMPONENTS Core Network REQUIRED)
-else(o2_WITH_QT5)
-    set(QT_USE_QTNETWORK true)
-    set(QT_USE_QTSCRIPT true)
-    find_package(Qt4 REQUIRED)
-endif(o2_WITH_QT5)
-#find_package(QJson REQUIRED)
-
-if (NOT o2_WITH_QT5)
-    include( ${QT_USE_FILE} )
-endif(NOT o2_WITH_QT5)
-
+endif()
 
 set( o2_SRCS
     o2.cpp
@@ -205,10 +197,6 @@ if(o2_WITH_KEYCHAIN)
 
 endif(o2_WITH_KEYCHAIN)
 
-if(NOT o2_WITH_QT5)
-    add_definitions(${QT4_DEFINITIONS})
-endif(NOT o2_WITH_QT5)
-
 if(BUILD_SHARED_LIBS AND APPLE AND POLICY CMP0042) # in CMake >= 2.8.12
     cmake_policy(SET CMP0042 OLD)
     set(CMAKE_MACOSX_RPATH OFF) # don't embed @rpath in install name
@@ -220,11 +208,7 @@ if(BUILD_SHARED_LIBS)
     add_definitions( -DO2_SHARED_LIB )
 endif(BUILD_SHARED_LIBS)
 
-if(o2_WITH_QT5)
-    target_link_libraries( o2 Qt5::Core Qt5::Network ${LINK_TARGETS})
-else(o2_WITH_QT5)
-    target_link_libraries( o2 ${QT_LIBRARIES} ${LINK_TARGETS})
-endif(o2_WITH_QT5)
+target_link_libraries( o2 Qt::Core Qt::Network ${LINK_TARGETS})
 
 if(BUILD_SHARED_LIBS)
     if(APPLE)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 4fa2f60..671de99 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,10 +7,10 @@ set(CMAKE_AUTORCC ON)
 set(CMAKE_AUTOUIC ON)
 
 # Find Qt packages needed for testing
-if(o2_WITH_QT5)
-    find_package(Qt5 5.15 COMPONENTS Core Network Test REQUIRED)
-else()
+if(o2_WITH_QT6)
     find_package(Qt6 COMPONENTS Core Network Test REQUIRED)
+else()
+    find_package(Qt5 5.15 COMPONENTS Core Network Test REQUIRED)
 endif()
 
 # Source files from src directory