diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index 980eebe847..345361566e 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -96,7 +96,8 @@
 #define OPTEE_KNOWN_NSEC_CAPS OPTEE_SMC_NSEC_CAP_UNIPROCESSOR
 #define OPTEE_KNOWN_SEC_CAPS (OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM | \
                               OPTEE_SMC_SEC_CAP_UNREGISTERED_SHM | \
-                              OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
+                              OPTEE_SMC_SEC_CAP_DYNAMIC_SHM | \
+                              OPTEE_SMC_SEC_CAP_MEMREF_NULL)
 
 enum optee_call_state {
     OPTEE_CALL_NORMAL,
diff --git a/xen/include/asm-arm/tee/optee_smc.h b/xen/include/asm-arm/tee/optee_smc.h
index d568bb2fe1..2f5c702326 100644
--- a/xen/include/asm-arm/tee/optee_smc.h
+++ b/xen/include/asm-arm/tee/optee_smc.h
@@ -244,6 +244,9 @@
  */
 #define OPTEE_SMC_SEC_CAP_DYNAMIC_SHM		(1 << 2)
 
+/* Secure world supports Shared Memory with a NULL reference */
+#define OPTEE_SMC_SEC_CAP_MEMREF_NULL		(1 << 4)
+
 #define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES	9
 #define OPTEE_SMC_EXCHANGE_CAPABILITIES \
 	OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES)