diff --git a/pinos/gst/gstpinosclock.c b/pinos/gst/gstpinosclock.c
index 0a03992e9..8e8583dc1 100644
--- a/pinos/gst/gstpinosclock.c
+++ b/pinos/gst/gstpinosclock.c
@@ -50,7 +50,11 @@ gst_pinos_clock_get_internal_time (GstClock * clock)
 
   pinos_stream_get_time (pclock->stream, &t);
 
-  result = gst_util_uint64_scale_int (t.ticks, GST_SECOND, t.rate);
+  if (t.rate)
+    result = gst_util_uint64_scale_int (t.ticks, GST_SECOND, t.rate);
+  else
+    result = GST_CLOCK_TIME_NONE;
+
   GST_DEBUG ("%"PRId64", %d %"PRId64, t.ticks, t.rate, result);
 
   return result;
diff --git a/pinos/gst/gstpinosdeviceprovider.c b/pinos/gst/gstpinosdeviceprovider.c
index 04212d786..807b1bf26 100644
--- a/pinos/gst/gstpinosdeviceprovider.c
+++ b/pinos/gst/gstpinosdeviceprovider.c
@@ -207,13 +207,17 @@ new_node (const PinosNodeInfo *info)
     type = GST_PINOS_DEVICE_TYPE_SINK;
 
     for (i = 0; i < info->n_input_formats; i++) {
-      gst_caps_append (caps, gst_caps_from_format (info->input_formats[i]));
+      GstCaps *c1 = gst_caps_from_format (info->input_formats[i]);
+      if (c1)
+        gst_caps_append (caps, c1);
     }
   }
   else if (info->max_outputs > 0 && info->max_inputs == 0) {
     type = GST_PINOS_DEVICE_TYPE_SOURCE;
     for (i = 0; i < info->n_output_formats; i++) {
-      gst_caps_append (caps, gst_caps_from_format (info->output_formats[i]));
+      GstCaps *c1 = gst_caps_from_format (info->output_formats[i]);
+      if (c1)
+        gst_caps_append (caps, c1);
     }
   } else {
     type = GST_PINOS_DEVICE_TYPE_UNKNOWN;