diff --git a/sys/dev/isp/ispmbox.h b/sys/dev/isp/ispmbox.h
index 7a787fda1e7..86f5bda21bd 100644
--- a/sys/dev/isp/ispmbox.h
+++ b/sys/dev/isp/ispmbox.h
@@ -118,6 +118,7 @@
 
 /* These are for the ISP2100 FC cards */
 #define	MBOX_GET_LOOP_ID		0x20
+#define	MBOX_GET_RESOURCE_COUNT		0x42
 #define	MBOX_EXEC_COMMAND_IOCB_A64	0x54
 #define	MBOX_INIT_FIRMWARE		0x60
 #define	MBOX_GET_INIT_CONTROL_BLOCK	0x61