diff --git a/include/exec/memattrs.h b/include/exec/memattrs.h
index 4fde4eee8439..060b7e713149 100644
--- a/include/exec/memattrs.h
+++ b/include/exec/memattrs.h
@@ -64,6 +64,8 @@ typedef struct MemTxAttrs {
     uint16_t _reserved2;
 } MemTxAttrs;
 
+QEMU_BUILD_BUG_ON(sizeof(MemTxAttrs) > 8);
+
 /* Bus masters which don't specify any attributes will get this,
  * which has all attribute bits clear except the topmost one
  * (so that we can distinguish "all attributes deliberately clear"