diff --git a/include/arch/aarch64/arch.h b/include/arch/aarch64/arch.h
index 2ce1be8..dee7fdc 100644
--- a/include/arch/aarch64/arch.h
+++ b/include/arch/aarch64/arch.h
@@ -1234,6 +1234,8 @@
 #define GPCCR_EL3			S3_6_C2_C1_6
 #define GPTBR_EL3			S3_6_C2_C1_4
 
+#define SCXTNUM_EL2			S3_4_C13_C0_7
+
 /*******************************************************************************
  * RAS system registers
  ******************************************************************************/