diff --git a/proto/observation/v1.proto b/proto/observation/v1.proto
index 02e45ca..d013fe0 100644
--- a/proto/observation/v1.proto
+++ b/proto/observation/v1.proto
@@ -68,7 +68,7 @@ message Observation_1 {
   }
   optional Metadata metadata = 9;
 
-  PresetRef presetRef = 10;
+  optional PresetRef presetRef = 10;
 
   message PresetRef {
     bytes docId = 1;
diff --git a/schema/observation/v1.json b/schema/observation/v1.json
index 044d168..04d3d6e 100644
--- a/schema/observation/v1.json
+++ b/schema/observation/v1.json
@@ -197,6 +197,6 @@
       "required": ["docId", "versionId"]
     }
   },
-  "required": ["schemaName", "tags", "attachments", "metadata", "presetRef"],
+  "required": ["schemaName", "tags", "attachments", "metadata"],
   "additionalProperties": false
 }
diff --git a/src/lib/decode-conversions.ts b/src/lib/decode-conversions.ts
index 02be213..1b9aed1 100644
--- a/src/lib/decode-conversions.ts
+++ b/src/lib/decode-conversions.ts
@@ -80,15 +80,14 @@ export const convertObservation: ConvertFunction<'observation'> = (
   const jsonSchemaCommon = convertCommon(common, versionObj)
   let presetRef
 
-  if (!rest.presetRef) {
-    throw new Error('missing presetRef on observation')
-  }
-  if (!rest.presetRef.versionId) {
-    throw new Error('found presetRef on observation but is missing versionId')
-  }
-  presetRef = {
-    docId: rest.presetRef.docId.toString('hex'),
-    versionId: getVersionId(rest.presetRef.versionId),
+  if (rest.presetRef) {
+    if (!rest.presetRef.versionId)
+      throw new Error('found presetRef on observation but is missing versionId')
+
+    presetRef = {
+      docId: rest.presetRef.docId.toString('hex'),
+      versionId: getVersionId(rest.presetRef.versionId),
+    }
   }
 
   const obs: Observation = {
diff --git a/src/lib/encode-conversions.ts b/src/lib/encode-conversions.ts
index 4b270f9..df54f09 100644
--- a/src/lib/encode-conversions.ts
+++ b/src/lib/encode-conversions.ts
@@ -105,6 +105,13 @@ export const convertObservation: ConvertFunction<'observation'> = (
   const metadata: Observation_1_Metadata = mapeoDoc.metadata && {
     ...Observation_1_Metadata.fromPartial(mapeoDoc.metadata),
   }
+  let presetRef
+  if (mapeoDoc.presetRef) {
+    presetRef = {
+      docId: Buffer.from(mapeoDoc.presetRef?.docId, 'hex'),
+      versionId: parseVersionId(mapeoDoc.presetRef?.versionId),
+    }
+  }
 
   return {
     common: convertCommon(mapeoDoc),
@@ -112,10 +119,7 @@ export const convertObservation: ConvertFunction<'observation'> = (
     attachments,
     tags: convertTags(mapeoDoc.tags),
     metadata,
-    presetRef: {
-      docId: Buffer.from(mapeoDoc.presetRef?.docId, 'hex'),
-      versionId: parseVersionId(mapeoDoc.presetRef?.versionId),
-    },
+    presetRef,
   }
 }
 
diff --git a/test/fixtures/good-docs-minimal.js b/test/fixtures/good-docs-minimal.js
index 6d72a84..c5708bf 100644
--- a/test/fixtures/good-docs-minimal.js
+++ b/test/fixtures/good-docs-minimal.js
@@ -24,10 +24,6 @@ export const goodDocsMinimal = [
       attachments: [],
       tags: {},
       metadata: {},
-      presetRef: {
-        docId: cachedValues.refs.docId,
-        versionId: cachedValues.refs.versionId,
-      },
       deleted: false,
     },
     expected: {},