diff --git a/drivers/staging/greybus/es1-ap-usb.c b/drivers/staging/greybus/es1-ap-usb.c
index 1832d0f41b8a..f551907ced2d 100644
--- a/drivers/staging/greybus/es1-ap-usb.c
+++ b/drivers/staging/greybus/es1-ap-usb.c
@@ -127,6 +127,7 @@ static void hd_buffer_constraints(struct greybus_host_device *hd)
 	 */
 	hd->buffer_headroom = sizeof(u32);	/* For cport id */
 	hd->buffer_size_max = ES1_GBUF_MSG_SIZE_MAX;
+	BUILD_BUG_ON(hd->buffer_headroom > GB_BUFFER_HEADROOM_MAX);
 }
 
 #define ES1_TIMEOUT	500	/* 500 ms for the SVC to do something */
diff --git a/drivers/staging/greybus/greybus.h b/drivers/staging/greybus/greybus.h
index 8fda37c42a0c..11f4e5529d9a 100644
--- a/drivers/staging/greybus/greybus.h
+++ b/drivers/staging/greybus/greybus.h
@@ -69,6 +69,14 @@
 struct greybus_host_device;
 struct svc_msg;
 
+/*
+ * When the Greybus code allocates a buffer it sets aside bytes
+ * prior to the beginning of the payload area for the host device's
+ * exclusive use.  The size is specified by hd->buffer_headroom, and
+ * which can't be greater than GB_BUFFER_HEADROOM_MAX.
+ */
+#define GB_BUFFER_HEADROOM_MAX		sizeof(u64)
+
 /* Buffers allocated from the host driver will be aligned to this multiple */
 #define GB_BUFFER_ALIGN	sizeof(u32)