diff --git a/include/lib/cpus/aarch64/cortex_x2.h b/include/lib/cpus/aarch64/cortex_x2.h
index 9ce1223..3c315d5 100644
--- a/include/lib/cpus/aarch64/cortex_x2.h
+++ b/include/lib/cpus/aarch64/cortex_x2.h
@@ -20,4 +20,9 @@
 #define CORTEX_X2_CPUPWRCTLR_EL1				S3_0_C15_C2_7
 #define CORTEX_X2_CPUPWRCTLR_EL1_CORE_PWRDN_BIT			U(1)
 
+/*******************************************************************************
+ * CPU Auxiliary Control Register 5 definitions
+ ******************************************************************************/
+#define CORTEX_X2_CPUACTLR5_EL1					S3_0_C15_C8_0
+
 #endif /* CORTEX_X2_H */