diff --git a/HTAN.model.jsonld b/HTAN.model.jsonld
index de8bd16b..a6c0841c 100644
--- a/HTAN.model.jsonld
+++ b/HTAN.model.jsonld
@@ -27693,6 +27693,9 @@
                 },
                 {
                     "@id": "bts:Unknown"
+                },
+                {
+                    "@id": "bts:Unfixed"
                 }
             ],
             "sms:displayName": "Fixative Type",
@@ -57110,6 +57113,23 @@
             "sms:required": "sms:false",
             "sms:validationRules": []
         },
+        {
+            "@id": "bts:Unfixed",
+            "@type": "rdfs:Class",
+            "rdfs:comment": "TBD",
+            "rdfs:label": "Unfixed",
+            "rdfs:subClassOf": [
+                {
+                    "@id": "bts:FixativeType"
+                }
+            ],
+            "schema:isPartOf": {
+                "@id": "http://schema.biothings.io"
+            },
+            "sms:displayName": "Unfixed",
+            "sms:required": "sms:false",
+            "sms:validationRules": []
+        },
         {
             "@id": "bts:WarmIschemia",
             "@type": "rdfs:Class",