diff --git a/lib/shared/update-utils.js b/lib/shared/update-utils.js
--- a/lib/shared/update-utils.js
+++ b/lib/shared/update-utils.js
@@ -3,6 +3,7 @@
 import invariant from 'invariant';
 import _maxBy from 'lodash/fp/maxBy.js';
 
+import { updateSpecs } from './updates/update-specs.js';
 import { updateTypes } from '../types/update-types-enum.js';
 import {
   type ServerUpdateInfo,
@@ -21,23 +22,7 @@
 }
 
 function keyForUpdateData(updateData: UpdateData): ?string {
-  if (
-    updateData.type === updateTypes.UPDATE_THREAD ||
-    updateData.type === updateTypes.UPDATE_THREAD_READ_STATUS ||
-    updateData.type === updateTypes.DELETE_THREAD ||
-    updateData.type === updateTypes.JOIN_THREAD
-  ) {
-    return updateData.threadID;
-  } else if (updateData.type === updateTypes.UPDATE_ENTRY) {
-    return updateData.entryID;
-  } else if (updateData.type === updateTypes.UPDATE_CURRENT_USER) {
-    return updateData.userID;
-  } else if (updateData.type === updateTypes.DELETE_ACCOUNT) {
-    return updateData.deletedUserID;
-  } else if (updateData.type === updateTypes.UPDATE_USER) {
-    return updateData.updatedUserID;
-  }
-  return null;
+  return updateSpecs[updateData.type].keyForUpdateData?.(updateData) ?? null;
 }
 
 function keyForUpdateInfo(updateInfo: ServerUpdateInfo): ?string {
diff --git a/lib/shared/updates/delete-account-spec.js b/lib/shared/updates/delete-account-spec.js
--- a/lib/shared/updates/delete-account-spec.js
+++ b/lib/shared/updates/delete-account-spec.js
@@ -76,6 +76,9 @@
     updateTypes.DELETE_ACCOUNT,
     updateTypes.UPDATE_USER,
   ]),
+  keyForUpdateData(data: AccountDeletionUpdateData) {
+    return data.deletedUserID;
+  },
   typesOfReplacedUpdatesForMatchingKey: 'all_types',
   infoValidator: tShape<AccountDeletionUpdateInfo>({
     type: tNumber(updateTypes.DELETE_ACCOUNT),
diff --git a/lib/shared/updates/delete-thread-spec.js b/lib/shared/updates/delete-thread-spec.js
--- a/lib/shared/updates/delete-thread-spec.js
+++ b/lib/shared/updates/delete-thread-spec.js
@@ -64,6 +64,9 @@
     };
   },
   deleteCondition: 'all_types',
+  keyForUpdateData(data: ThreadDeletionUpdateData) {
+    return data.threadID;
+  },
   typesOfReplacedUpdatesForMatchingKey: 'all_types',
   infoValidator: tShape<ThreadDeletionUpdateInfo>({
     type: tNumber(updateTypes.DELETE_THREAD),
diff --git a/lib/shared/updates/join-thread-spec.js b/lib/shared/updates/join-thread-spec.js
--- a/lib/shared/updates/join-thread-spec.js
+++ b/lib/shared/updates/join-thread-spec.js
@@ -152,6 +152,9 @@
     };
   },
   deleteCondition: 'all_types',
+  keyForUpdateData(data: ThreadJoinUpdateData) {
+    return data.threadID;
+  },
   typesOfReplacedUpdatesForMatchingKey: 'all_types',
   infoValidator: tShape<ThreadJoinUpdateInfo>({
     type: tNumber(updateTypes.JOIN_THREAD),
diff --git a/lib/shared/updates/update-current-user-spec.js b/lib/shared/updates/update-current-user-spec.js
--- a/lib/shared/updates/update-current-user-spec.js
+++ b/lib/shared/updates/update-current-user-spec.js
@@ -58,6 +58,9 @@
     };
   },
   deleteCondition: new Set([updateTypes.UPDATE_CURRENT_USER]),
+  keyForUpdateData(data: CurrentUserUpdateData) {
+    return data.userID;
+  },
   typesOfReplacedUpdatesForMatchingKey: 'all_types',
   infoValidator: tShape<CurrentUserUpdateInfo>({
     type: tNumber(updateTypes.UPDATE_CURRENT_USER),
diff --git a/lib/shared/updates/update-entry-spec.js b/lib/shared/updates/update-entry-spec.js
--- a/lib/shared/updates/update-entry-spec.js
+++ b/lib/shared/updates/update-entry-spec.js
@@ -74,6 +74,9 @@
     };
   },
   deleteCondition: 'all_types',
+  keyForUpdateData(data: EntryUpdateData) {
+    return data.entryID;
+  },
   typesOfReplacedUpdatesForMatchingKey: 'all_types',
   infoValidator: tShape<EntryUpdateInfo>({
     type: tNumber(updateTypes.UPDATE_ENTRY),
diff --git a/lib/shared/updates/update-spec.js b/lib/shared/updates/update-spec.js
--- a/lib/shared/updates/update-spec.js
+++ b/lib/shared/updates/update-spec.js
@@ -91,6 +91,7 @@
     params: UpdateInfoFromRawInfoParams,
   ) => ?UpdateInfo,
   +deleteCondition: ?UpdateTypes,
+  +keyForUpdateData?: (data: Data) => string,
   +typesOfReplacedUpdatesForMatchingKey: ?UpdateTypes,
   +infoValidator: TType<UpdateInfo>,
 };
diff --git a/lib/shared/updates/update-thread-read-status-spec.js b/lib/shared/updates/update-thread-read-status-spec.js
--- a/lib/shared/updates/update-thread-read-status-spec.js
+++ b/lib/shared/updates/update-thread-read-status-spec.js
@@ -72,6 +72,9 @@
     };
   },
   deleteCondition: new Set([updateTypes.UPDATE_THREAD_READ_STATUS]),
+  keyForUpdateData(data: ThreadReadStatusUpdateData) {
+    return data.threadID;
+  },
   typesOfReplacedUpdatesForMatchingKey: new Set([
     updateTypes.UPDATE_THREAD_READ_STATUS,
   ]),
diff --git a/lib/shared/updates/update-thread-spec.js b/lib/shared/updates/update-thread-spec.js
--- a/lib/shared/updates/update-thread-spec.js
+++ b/lib/shared/updates/update-thread-spec.js
@@ -93,6 +93,9 @@
     updateTypes.UPDATE_THREAD,
     updateTypes.UPDATE_THREAD_READ_STATUS,
   ]),
+  keyForUpdateData(data: ThreadUpdateData) {
+    return data.threadID;
+  },
   typesOfReplacedUpdatesForMatchingKey: new Set([
     updateTypes.UPDATE_THREAD_READ_STATUS,
   ]),
diff --git a/lib/shared/updates/update-user-spec.js b/lib/shared/updates/update-user-spec.js
--- a/lib/shared/updates/update-user-spec.js
+++ b/lib/shared/updates/update-user-spec.js
@@ -43,6 +43,9 @@
     };
   },
   deleteCondition: new Set([updateTypes.UPDATE_USER]),
+  keyForUpdateData(data: UserUpdateData) {
+    return data.updatedUserID;
+  },
   typesOfReplacedUpdatesForMatchingKey: null,
   infoValidator: tShape<UserUpdateInfo>({
     type: tNumber(updateTypes.UPDATE_USER),