diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index eec0df6..5a1e097 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -97,7 +97,7 @@
 					      hf_ipaddr_t recv)
 {
 	return spci_call(
-		(struct spci_value){.func = SPCI_RXTX_MAP_32,
+		(struct spci_value){.func = SPCI_RXTX_MAP_64,
 				    .arg1 = send,
 				    .arg2 = recv,
 				    .arg3 = HF_MAILBOX_SIZE / SPCI_PAGE_SIZE});
diff --git a/inc/vmapi/hf/spci.h b/inc/vmapi/hf/spci.h
index a70dcdd..c7638ce 100644
--- a/inc/vmapi/hf/spci.h
+++ b/inc/vmapi/hf/spci.h
@@ -33,6 +33,7 @@
 #define SPCI_FEATURES_32              0x84000064
 #define SPCI_RX_RELEASE_32            0x84000065
 #define SPCI_RXTX_MAP_32              0x84000066
+#define SPCI_RXTX_MAP_64              0xC4000066
 #define SPCI_RXTX_UNMAP_32            0x84000067
 #define SPCI_PARTITION_INFO_GET_32    0x84000068
 #define SPCI_ID_GET_32                0x84000069