diff --git a/cmake/zephyr_module.cmake b/cmake/zephyr_module.cmake
index 6e3d60e05f1..c5fbc06ac88 100644
--- a/cmake/zephyr_module.cmake
+++ b/cmake/zephyr_module.cmake
@@ -123,4 +123,6 @@ else()
 
 endif()
 
-list(REMOVE_DUPLICATES ZEPHYR_MODULE_NAMES)
+if(DEFINED ZEPHYR_MODULE_NAMES)
+  list(REMOVE_DUPLICATES ZEPHYR_MODULE_NAMES)
+endif()