diff --git a/src/liboggz/oggz_auto.c b/src/liboggz/oggz_auto.c
index 5acbdfd7d9ea58004bacd0b3187e772853a3575f..50f204811b83384be5c2dd8f2eb60d9d9921e528 100644
--- a/src/liboggz/oggz_auto.c
+++ b/src/liboggz/oggz_auto.c
@@ -844,6 +844,9 @@ auto_calc_theora(ogg_int64_t now, oggz_stream_t *stream, ogg_packet *op) {
     }
     info->encountered_first_data_packet = 0;
     return (ogg_int64_t)0;
+  } else if (info == NULL) {
+    /* info can only be NULLL when first_byte bit 0x80 is set */
+    return (ogg_int64_t)-1;
   }
 
   /* known granulepos */