diff --git a/include/crm/pengine/complex.h b/include/crm/pengine/complex.h
index 9b6ad1b608..e194e5e3b8 100644
--- a/include/crm/pengine/complex.h
+++ b/include/crm/pengine/complex.h
@@ -1,37 +1,39 @@
 /*
  * Copyright 2004-2023 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
 
 #ifndef PCMK__CRM_PENGINE_COMPLEX__H
 #  define PCMK__CRM_PENGINE_COMPLEX__H
 
 #include <glib.h>                   // gboolean, GHashTable
 #include <libxml/tree.h>            // xmlNode
 #include <crm/pengine/pe_types.h>   // pcmk_node_t, pcmk_resource_t, etc.
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+// @COMPAT Make internal when we can break API backward compatibility
+//! \deprecated Do not use
 extern pcmk_rsc_methods_t resource_class_functions[];
 
 GHashTable *pe_rsc_params(pcmk_resource_t *rsc, const pcmk_node_t *node,
                           pcmk_scheduler_t *scheduler);
 void get_meta_attributes(GHashTable * meta_hash, pcmk_resource_t *rsc,
                          pcmk_node_t *node, pcmk_scheduler_t *scheduler);
 void get_rsc_attributes(GHashTable *meta_hash, const pcmk_resource_t *rsc,
                         const pcmk_node_t *node, pcmk_scheduler_t *scheduler);
 
 gboolean is_parent(pcmk_resource_t *child, pcmk_resource_t *rsc);
 pcmk_resource_t *uber_parent(pcmk_resource_t *rsc);
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif