diff --git a/pam_usb/src/volume.c b/pam_usb/src/volume.c
index 928cca3..202e443 100644
--- a/pam_usb/src/volume.c
+++ b/pam_usb/src/volume.c
@@ -79,6 +79,11 @@ static LibHalVolume	*pusb_volume_probe(t_pusb_options *opts,
   int			maxtries = 0;
   int			i;
 
+  if (!*(opts->device.volume_uuid))
+    {
+      log_debug("No UUID configured for device\n");
+      return (NULL);
+    }
   log_debug("Searching for volume with uuid %s\n", opts->device.volume_uuid);
   maxtries = ((opts->probe_timeout * 1000000) / 250000);
   for (i = 0; i < maxtries; ++i)
diff --git a/pam_usb/src/xpath.c b/pam_usb/src/xpath.c
index 0e19abd..40ec8a6 100644
--- a/pam_usb/src/xpath.c
+++ b/pam_usb/src/xpath.c
@@ -65,6 +65,12 @@ int			pusb_xpath_get_string(xmlDocPtr doc, const char *path,
 
   node = result->nodesetval->nodeTab[0]->xmlChildrenNode;
   result_string = xmlNodeListGetString(doc, node, 1);
+  if (!result_string)
+    {
+      xmlXPathFreeObject(result);
+      log_debug("Empty value for %s\n", path);
+      return (0);
+    }
   if (strlen((const char *)result_string) + 1 > size)
     {
       xmlFree(result_string);