diff --git a/plat/arm/board/morello/include/platform_def.h b/plat/arm/board/morello/include/platform_def.h
index 993aa46..3cf723e 100644
--- a/plat/arm/board/morello/include/platform_def.h
+++ b/plat/arm/board/morello/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2023, Arm Limited. All rights reserved.
+ * Copyright (c) 2020-2024, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -59,6 +59,10 @@
 
 #if CSS_USE_SCMI_SDS_DRIVER
 #define MORELLO_SCMI_PAYLOAD_BASE		ULL(0x45400000)
+/*
+ * Index of SDS region used in the communication with SCP
+ */
+#define SDS_SCP_AP_REGION_ID			U(0)
 #else
 #define PLAT_CSS_SCP_COM_SHARED_MEM_BASE	ULL(0x45400000)
 #endif