diff --git a/CMake/FindPEGTL.cmake b/CMake/FindPEGTL.cmake
index f9a8846..f9ac9ca 100644
--- a/CMake/FindPEGTL.cmake
+++ b/CMake/FindPEGTL.cmake
@@ -24,7 +24,13 @@ message(STATUS "Searching for PEGTL")
 find_package(PEGTL CONFIG REQUIRED)
 if(TARGET taocpp::pegtl)
     message(STATUS "Searching for PEGTL - found target taocpp::pegtl")
-    set_target_properties(taocpp::pegtl PROPERTIES IMPORTED_GLOBAL TRUE)
+    # CMake 4 forbids promoting an imported target to global scope from a
+    # child directory; consumers such as f3d call find_package(VTK) inside a
+    # function. Only promote if not already global to avoid a hard error.
+    get_target_property(_vtk_pegtl_global taocpp::pegtl IMPORTED_GLOBAL)
+    if(NOT _vtk_pegtl_global)
+      set_target_properties(taocpp::pegtl PROPERTIES IMPORTED_GLOBAL TRUE)
+    endif()
     if(NOT TARGET PEGTL::PEGTL)
        add_library(PEGTL::PEGTL IMPORTED INTERFACE)
        target_link_libraries(PEGTL::PEGTL INTERFACE taocpp::pegtl)