diff --git a/CMakeLists.txt b/CMakeLists.txt
index bf12898..6fc94ae 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,12 +8,12 @@ if (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
 endif()
 
 option(ENABLE_QT4 "Building Qt4 plugin." OFF)
-option(ENABLE_QT5 "Building Qt5 plugin." OFF)
+option(ENABLE_QT5 "Building Qt5 plugin." ON)
 option(WITHOUT_KF "Compiling without KDE Frameworks..." OFF)
 
 add_subdirectory(style)
 if(NOT ENABLE_QT4)
-  if(NOT ENABLE_QT5)
+  if(ENABLE_QT5)
     add_subdirectory(kvantumpreview)
     add_subdirectory(kvantummanager)
     add_subdirectory(themes)
diff --git a/kvantummanager/CMakeLists.txt b/kvantummanager/CMakeLists.txt
index 89e2558..c5d61c0 100644
--- a/kvantummanager/CMakeLists.txt
+++ b/kvantummanager/CMakeLists.txt
@@ -1,12 +1,11 @@
 set(QT5_MINIMUM_VERSION "5.15.0")
 set(QT6_MINIMUM_VERSION "6.2.0")
 
-if(NOT ENABLE_QT5)
-  set(QT_VERSION_MAJOR 6)
-  find_package(Qt6 "${QT6_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets Svg)
-else()
+if(ENABLE_QT5)
   set(QT_VERSION_MAJOR 5)
   find_package(Qt5 "${QT5_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets Svg)
+else()
+  message(FATAL_ERROR "Non-Qt5 is not supported in this build.")
 endif()
 
 find_package(Qt${QT_VERSION_MAJOR} QUIET COMPONENTS LinguistTools)
diff --git a/kvantumpreview/CMakeLists.txt b/kvantumpreview/CMakeLists.txt
index ab934b5..30c493a 100644
--- a/kvantumpreview/CMakeLists.txt
+++ b/kvantumpreview/CMakeLists.txt
@@ -1,12 +1,11 @@
 set(QT5_MINIMUM_VERSION "5.15.0")
 set(QT6_MINIMUM_VERSION "6.2.0")
 
-if(NOT ENABLE_QT5)
-  set(QT_VERSION_MAJOR 6)
-  find_package(Qt6 "${QT6_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets)
-else()
+if(ENABLE_QT5)
   set(QT_VERSION_MAJOR 5)
   find_package(Qt5 "${QT5_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets)
+else()
+  message(FATAL_ERROR "Non-Qt5 is not supported in this build.")
 endif()
 
 find_package(Qt${QT_VERSION_MAJOR} QUIET COMPONENTS LinguistTools)
diff --git a/style/CMakeLists.txt b/style/CMakeLists.txt
index e59cb61..48c6e47 100644
--- a/style/CMakeLists.txt
+++ b/style/CMakeLists.txt
@@ -4,25 +4,15 @@ set(KF5_MINIMUM_VERSION "5.82.0")
 set(KF6_MINIMUM_VERSION "6.0.0")
 
 if(NOT ENABLE_QT4)
-  if(NOT ENABLE_QT5)
-    set(QT_VERSION_MAJOR 6)
-    find_package(Qt6 "${QT6_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets Svg)
-    if(NOT WITHOUT_KF)
-      find_package(KF6WindowSystem "${KF6_MINIMUM_VERSION}" REQUIRED)
-    endif()
-  else()
+  if(ENABLE_QT5)
     set(QT_VERSION_MAJOR 5)
     find_package(Qt5 "${QT5_MINIMUM_VERSION}" REQUIRED COMPONENTS Core Gui Widgets Svg X11Extras)
     if(NOT WITHOUT_KF)
-      find_package(KF5WindowSystem "${KF5_MINIMUM_VERSION}" REQUIRED)
+        find_package(KF5WindowSystem "${KF5_MINIMUM_VERSION}" REQUIRED)
     endif()
+  else()
+    message(FATAL_ERROR "Non-Qt5 is not supported in this build.")
   endif()
-else()
-  set(QT_VERSION_MAJOR 4)
-  find_package(Qt4 4.8.7 REQUIRED)
-
-  include(${QT_USE_FILE})
-  add_definitions(${QT_DEFINITIONS})
 endif()
 
 find_package(X11 REQUIRED)