diff --git a/include/lib/cpus/aarch64/cortex_a78.h b/include/lib/cpus/aarch64/cortex_a78.h
index 31da99e..fb325b6 100644
--- a/include/lib/cpus/aarch64/cortex_a78.h
+++ b/include/lib/cpus/aarch64/cortex_a78.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2022, ARM Limited. All rights reserved.
+ * Copyright (c) 2019-2023, ARM Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -40,6 +40,8 @@
 #define CORTEX_A78_ACTLR2_EL1_BIT_2			(ULL(1) << 2)
 #define CORTEX_A78_ACTLR2_EL1_BIT_40			(ULL(1) << 40)
 
+#define CORTEX_A78_ACTLR3_EL1				S3_0_C15_C1_2
+
 /*******************************************************************************
  * CPU Activity Monitor Unit register specific definitions.
  ******************************************************************************/