diff --git a/recording-daemon/metafile.c b/recording-daemon/metafile.c
index aa245c1d5..b77b68da1 100644
--- a/recording-daemon/metafile.c
+++ b/recording-daemon/metafile.c
@@ -104,7 +104,7 @@ static void meta_mix_output(metafile_t *mf) {
 	mf->mix_out = output_new_ext(mf, "mix", "mixed", "mix");
 	if (mix_method == MM_CHANNELS)
 		mf->mix_out->channel_mult = mix_num_inputs;
-	mf->mix = mix_new();
+	mf->mix = mix_new(mf->media_rec_slots);
 	db_do_stream(mf, mf->mix_out, NULL, 0);
 }
 
@@ -127,6 +127,7 @@ static void meta_stream_details(metafile_t *mf, unsigned long snum, char *conten
 				&tag, &media, &tm, &cmp, &flags, &media_sdp_id, &media_rec_slot, &media_rec_slots) != 8)
 		return;
 
+	mf->media_rec_slots = media_rec_slots;
 	mix_set_channel_slots(mf->mix, media_rec_slots);
 	stream_details(mf, snum, tag, media_sdp_id, media_rec_slot-1);
 }
diff --git a/recording-daemon/mix.c b/recording-daemon/mix.c
index 7039c270c..751dfeea6 100644
--- a/recording-daemon/mix.c
+++ b/recording-daemon/mix.c
@@ -249,7 +249,7 @@ err:
 }
 
 
-mix_t *mix_new(void) {
+mix_t *mix_new(unsigned int media_rec_slots) {
 	mix_t *mix = g_new0(mix_t, 1);
 	format_init(&mix->in_format);
 	format_init(&mix->out_format);
@@ -265,6 +265,8 @@ mix_t *mix_new(void) {
 		mix->next_idx[i] = i;
 	}
 
+	mix_set_channel_slots(mix, media_rec_slots);
+
 	return mix;
 }
 
diff --git a/recording-daemon/mix.h b/recording-daemon/mix.h
index 65eeade5d..d64b4b0c8 100644
--- a/recording-daemon/mix.h
+++ b/recording-daemon/mix.h
@@ -6,7 +6,7 @@
 
 #define MIX_MAX_INPUTS 4
 
-mix_t *mix_new(void);
+mix_t *mix_new(unsigned int);
 void mix_destroy(mix_t *mix);
 void mix_set_channel_slots(mix_t *mix, unsigned int);
 bool mix_config(sink_t *, const format_t *requested_format, format_t *actual_format);
diff --git a/recording-daemon/types.h b/recording-daemon/types.h
index 40c5afeee..c59cc8ba6 100644
--- a/recording-daemon/types.h
+++ b/recording-daemon/types.h
@@ -151,6 +151,7 @@ struct metafile_s {
 	unsigned long long db_id;
 	unsigned int db_streams;
 	int64_t start_time_us;
+	unsigned int media_rec_slots;
 
 	GStringChunk *gsc; // XXX limit max size