diff --git a/api/so/sprk/actor/getPreferences.ts b/api/so/sprk/actor/getPreferences.ts
index da880be..cfaecd6 100644
--- a/api/so/sprk/actor/getPreferences.ts
+++ b/api/so/sprk/actor/getPreferences.ts
@@ -42,7 +42,9 @@ export default function (server: Server, ctx: AppContext) {
           for (const pref of userPref.contentLabelPrefs) {
             preferences.push({
               $type: "so.sprk.actor.defs#contentLabelPref",
-              labelerDid: pref.labelerDid as DidString | undefined,
+              ...(pref.labelerDid === undefined
+                ? {}
+                : { labelerDid: pref.labelerDid as DidString }),
               label: pref.label,
               visibility: pref.visibility as ContentLabelPref["visibility"],
             });
diff --git a/api/so/sprk/actor/putPreferences.ts b/api/so/sprk/actor/putPreferences.ts
index b1dfb90..478cc9b 100644
--- a/api/so/sprk/actor/putPreferences.ts
+++ b/api/so/sprk/actor/putPreferences.ts
@@ -50,7 +50,9 @@ export default function (server: Server, ctx: AppContext) {
             case "so.sprk.actor.defs#contentLabelPref": {
               const p = pref as ContentLabelPref;
               contentLabelPrefs.push({
-                labelerDid: p.labelerDid,
+                ...(p.labelerDid === undefined
+                  ? {}
+                  : { labelerDid: p.labelerDid }),
                 label: p.label,
                 visibility: p.visibility,
               });
diff --git a/tests/preferences_test.ts b/tests/preferences_test.ts
index b1af3dd..050098c 100644
--- a/tests/preferences_test.ts
+++ b/tests/preferences_test.ts
@@ -18,7 +18,10 @@ interface PutPreferencesArgs {
     body: {
       preferences: Array<{
         $type: string;
-        enabled: boolean;
+        enabled?: boolean;
+        labelerDid?: string;
+        label?: string;
+        visibility?: string;
       }>;
     };
   };
@@ -115,3 +118,77 @@ Deno.test("Spark adult content preference round-trips when disabled", async () =
     enabled: false,
   }]);
 });
+
+Deno.test("global content label preference omits labelerDid", async () => {
+  const userDid = "did:plc:testuser";
+  let storedPreferences: Partial<PreferenceDocument> = {};
+
+  const ctx = {
+    authVerifier: {
+      standard: {},
+    },
+    dataplane: {
+      preferences: {
+        putPreferences: (
+          did: string,
+          preferences: Partial<PreferenceDocument>,
+        ) => {
+          assertEquals(did, userDid);
+          storedPreferences = preferences;
+          return Promise.resolve();
+        },
+        getPreferences: (did: string) => {
+          assertEquals(did, userDid);
+          return Promise.resolve({
+            userDid,
+            createdAt: "2026-08-14T00:00:00.000Z",
+            updatedAt: "2026-08-14T00:00:00.000Z",
+            ...storedPreferences,
+          });
+        },
+      },
+    },
+  } as unknown as AppContext;
+
+  let putHandler: PutPreferencesHandler = () =>
+    Promise.reject(new Error("putPreferences handler was not registered"));
+  putPreferences(
+    handlerServer((handler: PutPreferencesHandler) => putHandler = handler),
+    ctx,
+  );
+
+  await putHandler({
+    auth: { credentials: { iss: userDid } },
+    input: {
+      body: {
+        preferences: [{
+          $type: "so.sprk.actor.defs#contentLabelPref",
+          label: "sexual",
+          visibility: "warn",
+        }],
+      },
+    },
+  });
+
+  assertEquals(storedPreferences.contentLabelPrefs, [{
+    label: "sexual",
+    visibility: "warn",
+  }]);
+
+  let getHandler: GetPreferencesHandler = () =>
+    Promise.reject(new Error("getPreferences handler was not registered"));
+  getPreferences(
+    handlerServer((handler: GetPreferencesHandler) => getHandler = handler),
+    ctx,
+  );
+
+  const response = await getHandler({
+    auth: { credentials: { iss: userDid } },
+  });
+
+  assertEquals(response.body.preferences, [{
+    $type: "so.sprk.actor.defs#contentLabelPref",
+    label: "sexual",
+    visibility: "warn",
+  }]);
+});