diff --git a/NetworkPkg/HttpBootDxe/HttpBootDhcp6.h b/NetworkPkg/HttpBootDxe/HttpBootDhcp6.h
index f9eec9d7d3..14d6db0648 100644
--- a/NetworkPkg/HttpBootDxe/HttpBootDhcp6.h
+++ b/NetworkPkg/HttpBootDxe/HttpBootDhcp6.h
@@ -50,7 +50,7 @@ typedef struct {
 } HTTP_BOOT_DHCP6_OPTION_ARCH;
 
 typedef struct {
-  UINT8 ClassIdentifier[10];
+  UINT8 ClassIdentifier[11];
   UINT8 ArchitecturePrefix[5];
   UINT8 ArchitectureType[5];
   UINT8 Lit3[1];