diff --git a/src/client.ts b/src/client.ts
index 850803a17a..52029ce475 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -6980,6 +6980,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      */
     public async doesServerSupportExtendedProfiles(): Promise<boolean> {
         return (
+            (await this.isVersionSupported("v1.16")) ||
             (await this.doesServerSupportUnstableFeature(UNSTABLE_MSC4133_EXTENDED_PROFILES)) ||
             (await this.doesServerSupportUnstableFeature(STABLE_MSC4133_EXTENDED_PROFILES))
         );
@@ -6991,7 +6992,10 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns The prefix for use with `authedRequest`
      */
     private async getExtendedProfileRequestPrefix(): Promise<string> {
-        if (await this.doesServerSupportUnstableFeature("uk.tcpip.msc4133.stable")) {
+        if (
+            (await this.isVersionSupported("v1.16")) ||
+            (await this.doesServerSupportUnstableFeature("uk.tcpip.msc4133.stable"))
+        ) {
             return ClientPrefix.V3;
         }
         return "/_matrix/client/unstable/uk.tcpip.msc4133";
diff --git a/src/models/profile-keys.ts b/src/models/profile-keys.ts
index c33256233f..6075f9aa68 100644
--- a/src/models/profile-keys.ts
+++ b/src/models/profile-keys.ts
@@ -1,8 +1,33 @@
+/*
+Copyright 2025 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/**
+ * The timezone the user is currently in. The value of this property should
+ * match a timezone provided in https://www.iana.org/time-zones.
+ *
+ * This key was introduced in Matrix v1.16.
+ */
+export const ProfileKeyTimezone = "m.tz";
+
 /**
  * The timezone the user is currently in. The value of this property should
  * match a timezone provided in https://www.iana.org/time-zones.
  *
  * @see https://github.com/matrix-org/matrix-spec-proposals/blob/clokep/profile-tz/proposals/4175-profile-field-time-zone.md
  * @experimental
+ * @deprecated Unstable MSC field - Use `ProfileKeyTimezone`
  */
 export const ProfileKeyMSC4175Timezone = "us.cloke.msc4175.tz";
diff --git a/src/serverCapabilities.ts b/src/serverCapabilities.ts
index 3d3387fe43..15db201c63 100644
--- a/src/serverCapabilities.ts
+++ b/src/serverCapabilities.ts
@@ -64,6 +64,10 @@ export interface Capabilities {
     "m.set_displayname"?: ISetDisplayNameCapability;
     "m.set_avatar_url"?: ISetAvatarUrlCapability;
     "uk.tcpip.msc4133.profile_fields"?: IProfileFieldsCapability;
+    /**
+     * Since Matrix v1.16
+     */
+    "m.profile_fields"?: IProfileFieldsCapability;
 }
 
 type CapabilitiesResponse = {