diff --git a/q2_qsip2/types/_formats.py b/q2_qsip2/types/_formats.py
index 967dd02..1545102 100644
--- a/q2_qsip2/types/_formats.py
+++ b/q2_qsip2/types/_formats.py
@@ -15,6 +15,7 @@
 import qiime2.plugin.model as model
 
 
+# TODO: communicate warning about using pickled data
 class QSIP2DataFormat(model.BinaryFileFormat):
     package = 'q2_qsip2.types.tests'