diff --git a/src/interface/efi/efidrvprefix.c b/src/interface/efi/efidrvprefix.c
index 4fbb19f..a8ef667 100644
--- a/src/interface/efi/efidrvprefix.c
+++ b/src/interface/efi/efidrvprefix.c
@@ -34,16 +34,25 @@ FILE_LICENCE ( GPL2_OR_LATER );
  */
 EFI_STATUS EFIAPI _efidrv_start ( EFI_HANDLE image_handle,
 				  EFI_SYSTEM_TABLE *systab ) {
+	EFI_BOOT_SERVICES *bs;
+	EFI_TPL saved_tpl;
 	EFI_STATUS efirc;
 
 	/* Initialise EFI environment */
 	if ( ( efirc = efi_init ( image_handle, systab ) ) != 0 )
 		return efirc;
 
+	/* Raise TPL */
+	bs = efi_systab->BootServices;
+	saved_tpl = bs->RaiseTPL ( TPL_CALLBACK );
+
 	/* Initialise iPXE environment */
 	initialise();
 	startup();
 
+	/* Restore TPL */
+	bs->RestoreTPL ( saved_tpl );
+
 	return 0;
 }