diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index a520bb6c3b..daa98d9498 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -253,18 +253,17 @@ endfunction()
 qt_setup_tool_path_command()
 
 # Platform define path, etc.
-set(QT_QMAKE_TARGET_MKSPEC "")
 if(WIN32)
     set(QT_DEFAULT_PLATFORM_DEFINITIONS UNICODE _UNICODE WIN32 _ENABLE_EXTENDED_ALIGNED_STORAGE)
     if(CMAKE_SIZEOF_VOID_P EQUAL 8)
         list(APPEND QT_DEFAULT_PLATFORM_DEFINITIONS WIN64 _WIN64)
     endif()
     if(MSVC)
-        set(QT_QMAKE_TARGET_MKSPEC win32-msvc)
+        set(QT_DEFAULT_MKSPEC win32-msvc)
     elseif(CLANG AND MINGW)
-        set(QT_QMAKE_TARGET_MKSPEC win32-clang-g++)
+        set(QT_DEFAULT_MKSPEC win32-clang-g++)
     elseif(MINGW)
-        set(QT_QMAKE_TARGET_MKSPEC win32-g++)
+        set(QT_DEFAULT_MKSPEC win32-g++)
     endif()
 
     if (MINGW)
@@ -272,27 +271,31 @@ if(WIN32)
     endif()
 elseif(LINUX)
     if(GCC)
-        set(QT_QMAKE_TARGET_MKSPEC linux-g++)
+        set(QT_DEFAULT_MKSPEC linux-g++)
     elseif(CLANG)
-        set(QT_QMAKE_TARGET_MKSPEC linux-clang)
+        set(QT_DEFAULT_MKSPEC linux-clang)
     elseif(ICC)
-        set(QT_QMAKE_TARGET_MKSPEC linux-icc-64)
+        set(QT_DEFAULT_MKSPEC linux-icc-64)
     endif()
 elseif(ANDROID)
     if(GCC)
-        set(QT_QMAKE_TARGET_MKSPEC android-g++)
+        set(QT_DEFAULT_MKSPEC android-g++)
     elseif(CLANG)
-        set(QT_QMAKE_TARGET_MKSPEC android-clang)
+        set(QT_DEFAULT_MKSPEC android-clang)
     endif()
 elseif(APPLE)
-    set(QT_QMAKE_TARGET_MKSPEC macx-clang)
+    set(QT_DEFAULT_MKSPEC macx-clang)
     if(MACOS)
         list(APPEND QT_DEFAULT_PLATFORM_DEFINITIONS GL_SILENCE_DEPRECATION)
     elseif(UIKIT)
         list(APPEND QT_DEFAULT_PLATFORM_DEFINITIONS GLES_SILENCE_DEPRECATION)
     endif()
 elseif(EMSCRIPTEN)
-    set(QT_QMAKE_TARGET_MKSPEC wasm-emscripten)
+    set(QT_DEFAULT_MKSPEC wasm-emscripten)
+endif()
+
+if(NOT QT_QMAKE_TARGET_MKSPEC)
+    set(QT_QMAKE_TARGET_MKSPEC "${QT_DEFAULT_MKSPEC}" CACHE STRING "QMake target mkspec")
 endif()
 
 if(CMAKE_CROSSCOMPILING)