diff --git a/xen/drivers/char/ehci-dbgp.c b/xen/drivers/char/ehci-dbgp.c
index 8a0b958506..bb9d3198d9 100644
--- a/xen/drivers/char/ehci-dbgp.c
+++ b/xen/drivers/char/ehci-dbgp.c
@@ -1465,7 +1465,7 @@ static struct ehci_dbgp ehci_dbgp = { .state = dbgp_unsafe, .phys_port = 1 };
 
 static char __initdata opt_dbgp[30];
 
-static int __init parse_ehci_dbgp(const char *opt)
+static int __init cf_check parse_ehci_dbgp(const char *opt)
 {
     if ( strncmp(opt, "ehci", 4) )
         return 0;
diff --git a/xen/drivers/char/xhci-dbc.c b/xen/drivers/char/xhci-dbc.c
index 5f92234a95..43ed64a004 100644
--- a/xen/drivers/char/xhci-dbc.c
+++ b/xen/drivers/char/xhci-dbc.c
@@ -1282,7 +1282,7 @@ struct dbc_dma_bufs {
 static struct dbc_dma_bufs __section(".bss.page_aligned") __aligned(PAGE_SIZE)
     dbc_dma_bufs;
 
-static int __init xhci_parse_dbgp(const char *opt_dbgp)
+static int __init cf_check xhci_parse_dbgp(const char *opt_dbgp)
 {
     struct dbc_uart *uart = &dbc_uart;
     struct dbc *dbc = &uart->dbc;