diff --git a/gst/gstdevice.c b/gst/gstdevice.c
index 9982509cb0..08404bb23e 100644
--- a/gst/gstdevice.c
+++ b/gst/gstdevice.c
@@ -190,6 +190,8 @@ gst_device_create_element (GstDevice * device, const gchar * name)
 {
   GstDeviceClass *klass = GST_DEVICE_GET_CLASS (device);
 
+  g_return_val_if_fail (GST_IS_DEVICE (device), NULL);
+
   if (klass->create_element)
     return klass->create_element (device, name);
   else
@@ -210,6 +212,8 @@ gst_device_create_element (GstDevice * device, const gchar * name)
 GstCaps *
 gst_device_get_caps (GstDevice * device)
 {
+  g_return_val_if_fail (GST_IS_DEVICE (device), NULL);
+
   if (device->priv->caps)
     return gst_caps_ref (device->priv->caps);
   else
@@ -229,6 +233,8 @@ gst_device_get_caps (GstDevice * device)
 gchar *
 gst_device_get_display_name (GstDevice * device)
 {
+  g_return_val_if_fail (GST_IS_DEVICE (device), NULL);
+
   return
       g_strdup (device->priv->display_name ? device->priv->display_name : "");
 }
@@ -248,6 +254,8 @@ gst_device_get_display_name (GstDevice * device)
 gchar *
 gst_device_get_device_class (GstDevice * device)
 {
+  g_return_val_if_fail (GST_IS_DEVICE (device), NULL);
+
   if (device->priv->device_class != NULL)
     return g_strdup (device->priv->device_class);
   else
@@ -276,6 +284,8 @@ gst_device_reconfigure_element (GstDevice * device, GstElement * element)
 {
   GstDeviceClass *klass = GST_DEVICE_GET_CLASS (device);
 
+  g_return_val_if_fail (GST_IS_DEVICE (device), FALSE);
+
   if (klass->reconfigure_element)
     return klass->reconfigure_element (device, element);
   else
@@ -299,6 +309,8 @@ gst_device_has_classesv (GstDevice * device, gchar ** classes)
 {
   g_return_val_if_fail (GST_IS_DEVICE (device), FALSE);
 
+  if (!classes)
+    return TRUE;
 
   for (; classes[0]; classes++) {
     const gchar *found;
@@ -340,6 +352,11 @@ gst_device_has_classes (GstDevice * device, const gchar * classes)
   gchar **classesv;
   gboolean res;
 
+  g_return_val_if_fail (GST_IS_DEVICE (device), FALSE);
+
+  if (!classes)
+    return TRUE;
+
   classesv = g_strsplit (classes, "/", 0);
 
   res = gst_device_has_classesv (device, classesv);