diff --git a/cmake/nuttx_add_library.cmake b/cmake/nuttx_add_library.cmake
index 997ed228ed7..b7f64e8bb8e 100644
--- a/cmake/nuttx_add_library.cmake
+++ b/cmake/nuttx_add_library.cmake
@@ -200,3 +200,22 @@ function(nuttx_library_import library_name library_path)
   set_target_properties(${library_name} PROPERTIES IMPORTED_LOCATION
                                                    ${library_path})
 endfunction()
+
+# nuttx_add_external_library
+#
+# the target library of add_library has been called in external CMakeLists.txt
+# so that they can be added to the final link
+#
+# Usually used with Nuttx to include an external system that already supports
+# CMake compilation
+function(nuttx_add_external_library target)
+  cmake_parse_arguments(ARGS MODE "" "" ${ARGN})
+  if(NOT ARGS_MODE)
+    set_property(GLOBAL APPEND PROPERTY NUTTX_SYSTEM_LIBRARIES ${target})
+  elseif("${ARGS_MODE}" STREQUAL "APPS")
+    set_property(GLOBAL APPEND PROPERTY NUTTX_APPS_LIBRARIES ${target})
+  elseif("${ARGS_MODE}" STREQUAL "KERNEL")
+    set_property(GLOBAL APPEND PROPERTY NUTTX_KERNEL_LIBRARIES ${target})
+  endif()
+  nuttx_add_library_internal(${target})
+endfunction()