diff --git a/express/properties/material.py b/express/properties/material.py
index feabd59b..da04c384 100644
--- a/express/properties/material.py
+++ b/express/properties/material.py
@@ -121,6 +121,7 @@ def _serialize(self):
                 "slug": ""
             },
             "schemaVersion": "0.2.0",
+            "isNonPeriodic": self.is_non_periodic,
         }
 
     def _elemental_ratios(self):
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 7d81def3..0d90fd71 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -5,7 +5,9 @@ click==7.0
 coverage==5.3
 cycler==0.10.0
 decorator==4.4.2
-esse==2021.09.09
+# esse==2021.09.09
+# -e ../esse
+git+https://git@github.com/Exabyte-io/esse@ecc26ff1bbf191f392572840faf20d145f93f659#egg=esse
 exabyte-json-include==2021.05.06
 flask==1.0.2
 idna==2.7