diff --git a/extlibs/libespfs b/extlibs/libespfs
index 5342a39..03ff681 160000
--- a/extlibs/libespfs
+++ b/extlibs/libespfs
@@ -1 +1 @@
-Subproject commit 5342a39a179a4dddede680615bf4694755d2a59d
+Subproject commit 03ff681a61cb03a43c6f008601a6e6090e9df2bd
diff --git a/src/WebGUIAppMain.c b/src/WebGUIAppMain.c
index a2087c1..855a39e 100644
--- a/src/WebGUIAppMain.c
+++ b/src/WebGUIAppMain.c
@@ -241,7 +241,7 @@ static void ResetSysConfig(SYS_CONFIG *Conf)
 
     UINT32_VAL d;
     GetChipId((uint8_t*) d.v);
-    snprintf(Conf->SN, 11, "%010d", (int)swap(d.Val));
+    snprintf(Conf->SN, 11, "%010u", (unsigned int)swap(d.Val));
 
     memcpy(Conf->NetBIOSName, CONFIG_WEBGUIAPP_HOSTNAME,
            sizeof(CONFIG_WEBGUIAPP_HOSTNAME));