diff --git a/gst/audiomixer/gstaudiomixer.c b/gst/audiomixer/gstaudiomixer.c
index 40ede84346..f0e8f66ebc 100644
--- a/gst/audiomixer/gstaudiomixer.c
+++ b/gst/audiomixer/gstaudiomixer.c
@@ -350,11 +350,12 @@ static gboolean
 gst_audiomixer_setcaps (GstAudioMixer * audiomixer, GstPad * pad,
     GstCaps * orig_caps)
 {
+  GstAggregator *agg = GST_AGGREGATOR (audiomixer);
   GstAudioAggregator *aagg = GST_AUDIO_AGGREGATOR (audiomixer);
   GstCaps *caps;
   GstAudioInfo info;
   GstStructure *s;
-  gint channels;
+  gint channels = 0;
   gboolean ret;
 
   caps = gst_caps_copy (orig_caps);
@@ -367,6 +368,31 @@ gst_audiomixer_setcaps (GstAudioMixer * audiomixer, GstPad * pad,
   if (!gst_audio_info_from_caps (&info, caps))
     goto invalid_format;
 
+  if (channels == 1) {
+    GstCaps *filter;
+    GstCaps *downstream_caps;
+
+    if (audiomixer->filter_caps)
+      filter = gst_caps_intersect_full (caps, audiomixer->filter_caps,
+          GST_CAPS_INTERSECT_FIRST);
+    else
+      filter = gst_caps_ref (caps);
+
+    downstream_caps = gst_pad_peer_query_caps (agg->srcpad, filter);
+    gst_caps_unref (filter);
+
+    if (downstream_caps) {
+      gst_caps_unref (caps);
+      caps = downstream_caps;
+
+      if (gst_caps_is_empty (caps)) {
+        gst_caps_unref (caps);
+        return FALSE;
+      }
+      caps = gst_caps_fixate (caps);
+    }
+  }
+
   GST_OBJECT_LOCK (audiomixer);
   /* don't allow reconfiguration for now; there's still a race between the
    * different upstream threads doing query_caps + accept_caps + sending
diff --git a/tests/check/elements/audiomixer.c b/tests/check/elements/audiomixer.c
index d758e75eea..b6235dce0c 100644
--- a/tests/check/elements/audiomixer.c
+++ b/tests/check/elements/audiomixer.c
@@ -89,7 +89,8 @@ GST_START_TEST (test_filter_caps)
   filter_caps = gst_caps_new_simple ("audio/x-raw",
       "format", G_TYPE_STRING, GST_AUDIO_NE (F32),
       "layout", G_TYPE_STRING, "interleaved",
-      "rate", G_TYPE_INT, 44100, "channels", G_TYPE_INT, 1, NULL);
+      "rate", G_TYPE_INT, 44100, "channels", G_TYPE_INT, 1,
+      "channel-mask", GST_TYPE_BITMASK, 0x04, NULL);
 
   /* build pipeline */
   pipeline = gst_pipeline_new ("pipeline");