diff --git a/cmake/QtInternalTargets.cmake b/cmake/QtInternalTargets.cmake
index cdaa91ffcb4..a04e2169435 100644
--- a/cmake/QtInternalTargets.cmake
+++ b/cmake/QtInternalTargets.cmake
@@ -6,7 +6,7 @@ function(qt_internal_set_warnings_are_errors_flags target)
         if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "3.0.0")
             list(APPEND flags -Werror -Wno-error=\#warnings -Wno-error=deprecated-declarations)
         endif()
-        if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
+        if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
             # Clang will otherwise show error about inline method conflicting with dllimport class attribute in tools
             # (this was tested with Clang 10)
             #    error: 'QString::operator[]' redeclared inline; 'dllimport' attribute ignored [-Werror,-Wignored-attributes]