diff --git a/os/kernel/include/chthreads.h b/os/kernel/include/chthreads.h
index 12d853eb1..e862c8c1a 100644
--- a/os/kernel/include/chthreads.h
+++ b/os/kernel/include/chthreads.h
@@ -160,7 +160,7 @@ struct Thread {
    */
   void                  *p_mpool;
 #endif
-#if defined(THREAD_EXT_FIELDS_HOOK)
+#if defined(THREAD_EXT_FIELDS)
   /* Extra fields defined in chconf.h.*/
   THREAD_EXT_FIELDS
 #endif