diff --git a/src/corelib/Qt6CoreMacros.cmake b/src/corelib/Qt6CoreMacros.cmake
index d014ebf5d9..bcb76d4256 100644
--- a/src/corelib/Qt6CoreMacros.cmake
+++ b/src/corelib/Qt6CoreMacros.cmake
@@ -1673,9 +1673,11 @@ function(_qt_internal_expose_deferred_files_to_ide target)
     endforeach()
 
     get_target_property(target_source_dir ${target} SOURCE_DIR)
+    get_filename_component(target_source_dir "${target_source_dir}" REALPATH)
     get_target_property(existing_sources ${target} SOURCES)
     if(existing_sources)
         set(existing_sources_real "")
+        set(realf "")
         foreach(f IN LISTS existing_sources)
             get_filename_component(realf "${f}" REALPATH BASE_DIR ${target_source_dir})
             list(APPEND existing_sources_real ${realf})
@@ -1685,12 +1687,20 @@ function(_qt_internal_expose_deferred_files_to_ide target)
     if("${new_sources_real}" STREQUAL "")
         return()
     endif()
-    target_sources(${target} PRIVATE ${new_sources_real})
+    # Need to convert real paths back to relative paths because the use of absolute paths for these
+    # files causes invalid generation of build.ninja on Windows platforms.
+    set(new_sources "")
+    foreach(realf IN LISTS new_sources_real)
+        file(RELATIVE_PATH f "${target_source_dir}" "${realf}")
+        list(APPEND new_sources "${f}")
+    endforeach()
+
+    target_sources(${target} PRIVATE ${new_sources})
     set(scope_args)
     if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.18")
         set(scope_args TARGET_DIRECTORY "${target}")
     endif()
-    set_source_files_properties(${new_sources_real} ${scope_args} PROPERTIES HEADER_FILE_ONLY ON)
+    set_source_files_properties(${new_sources} ${scope_args} PROPERTIES HEADER_FILE_ONLY ON)
 endfunction()
 
 #