diff --git a/gst-libs/gst/audio/audio.h b/gst-libs/gst/audio/audio.h
index a050e515fe..ed282fa732 100644
--- a/gst-libs/gst/audio/audio.h
+++ b/gst-libs/gst/audio/audio.h
@@ -250,6 +250,8 @@ struct _GstAudioInfo {
   GstAudioChannelPosition   position[64];
 };
 
+#define GST_AUDIO_INFO_IS_VALID(i)           ((i)->finfo != NULL && (i)->rate > 0 && (i)->channels > 0 && (i)->bpf > 0)
+
 #define GST_AUDIO_INFO_FORMAT(i)             (GST_AUDIO_FORMAT_INFO_FORMAT((i)->finfo))
 #define GST_AUDIO_INFO_NAME(i)               (GST_AUDIO_FORMAT_INFO_NAME((i)->finfo))
 #define GST_AUDIO_INFO_WIDTH(i)              (GST_AUDIO_FORMAT_INFO_WIDTH((i)->finfo))
diff --git a/gst-libs/gst/audio/gstaudiodecoder.c b/gst-libs/gst/audio/gstaudiodecoder.c
index 2e3d1986b4..5e2c631140 100644
--- a/gst-libs/gst/audio/gstaudiodecoder.c
+++ b/gst-libs/gst/audio/gstaudiodecoder.c
@@ -722,6 +722,9 @@ gst_audio_decoder_finish_frame (GstAudioDecoder * dec, GstBuffer * buf,
   priv = dec->priv;
   ctx = &dec->priv->ctx;
 
+  /* must know the output format by now */
+  g_return_val_if_fail (GST_AUDIO_INFO_IS_VALID (&ctx->info), GST_FLOW_ERROR);
+
   GST_LOG_OBJECT (dec, "accepting %d bytes == %d samples for %d frames",
       buf ? GST_BUFFER_SIZE (buf) : -1,
       buf ? GST_BUFFER_SIZE (buf) / ctx->info.bpf : -1, frames);