diff --git a/cmake/QtProcessConfigureArgs.cmake b/cmake/QtProcessConfigureArgs.cmake
index 0572fbbd5b8..8fa4be2af1a 100644
--- a/cmake/QtProcessConfigureArgs.cmake
+++ b/cmake/QtProcessConfigureArgs.cmake
@@ -54,7 +54,8 @@ if("${MODULE_ROOT}" STREQUAL "")
     get_filename_component(MODULE_ROOT ".." ABSOLUTE BASE_DIR "${CMAKE_CURRENT_LIST_DIR}")
     set(qtbase_or_top_level_build TRUE)
 else()
-    file(TO_CMAKE_PATH "${MODULE_ROOT}" MODULE_ROOT)
+    # If MODULE_ROOT is passed without drive letter, we try to add it to the path.
+    get_filename_component(MODULE_ROOT "." REALPATH BASE_DIR "${MODULE_ROOT}")
     set(qtbase_or_top_level_build FALSE)
 endif()
 set(configure_filename "configure.cmake")