diff --git a/include/xen/interface/xen-mca.h b/include/xen/interface/xen-mca.h
index 73a4ea714d93..5db6116cd042 100644
--- a/include/xen/interface/xen-mca.h
+++ b/include/xen/interface/xen-mca.h
@@ -365,7 +365,7 @@ struct xen_mce {
 #define XEN_MCE_LOG_LEN 32
 
 struct xen_mce_log {
-	char signature[12]; /* "MACHINECHECK" */
+	char signature[12] __nonstring; /* "MACHINECHECK" */
 	unsigned len;	    /* = XEN_MCE_LOG_LEN */
 	unsigned next;
 	unsigned flags;