diff --git a/src/Journal.tsx b/src/Journal.tsx
index e7cd9ef..da434b2 100644
--- a/src/Journal.tsx
+++ b/src/Journal.tsx
@@ -39,7 +39,7 @@ class Journal extends React.Component {
 
   render() {
     const journalUid = this.props.match.params.journalUid;
-    const entries = this.props.entries[journalUid];
+    const entries = this.props.entries.get(journalUid);
 
     if ((!entries) || (entries.value === null)) {
       return (<LoadingIndicator />);
diff --git a/src/JournalEntries.tsx b/src/JournalEntries.tsx
index f33c64b..5170bfd 100644
--- a/src/JournalEntries.tsx
+++ b/src/JournalEntries.tsx
@@ -1,3 +1,5 @@
+import * as Immutable from 'immutable';
+
 import * as React from 'react';
 import { List, ListItem } from 'material-ui/List';
 import Dialog from 'material-ui/Dialog';
@@ -23,7 +25,7 @@ class JournalEntries extends React.Component {
 
   props: {
     journal: EteSync.Journal,
-    entries: Array<EteSync.SyncEntry>,
+    entries: Immutable.List<EteSync.SyncEntry>,
   };
 
   constructor(props: any) {
diff --git a/src/Pim.tsx b/src/Pim.tsx
index ed77426..83d1b2c 100644
--- a/src/Pim.tsx
+++ b/src/Pim.tsx
@@ -49,7 +49,11 @@ class Pim extends React.Component {
       return;
     }
 
-    const entries = this.props.entries[journal.uid];
+    const entries = this.props.entries.get(journal.uid);
+
+    if (!entries) {
+      return;
+    }
 
     if (entries.value === null) {
       return;
@@ -91,7 +95,7 @@ class Pim extends React.Component {
     let collectionsCalendar: Array<EteSync.CollectionInfo> = [];
     const journalMap = this.props.journals.reduce(
       (ret, journal) => {
-        const journalEntries = this.props.entries[journal.uid];
+        const journalEntries = this.props.entries.get(journal.uid);
         const cryptoManager = new EteSync.CryptoManager(derived, journal.uid, journal.version);
 
         let prevUid: string | null = null;
diff --git a/src/SyncGate.tsx b/src/SyncGate.tsx
index b5748f3..ea2eb39 100644
--- a/src/SyncGate.tsx
+++ b/src/SyncGate.tsx
@@ -35,9 +35,10 @@ class SyncGate extends React.Component {
     if (nextProps.journals.value && (this.props.journals.value !== nextProps.journals.value)) {
       for (const journal of nextProps.journals.value) {
         let prevUid: string | null = null;
-        const entries = this.props.entries[journal.uid];
-        if (entries && entries.value && (entries.value.length > 0)) {
-          prevUid = entries.value[entries.value.length - 1].uid;
+        const entries = this.props.entries.get(journal.uid);
+        if (entries && entries.value) {
+          const last = entries.value.last();
+          prevUid = (last) ? last.uid : null;
         }
 
         store.dispatch(fetchEntries(this.props.etesync, journal.uid, prevUid));
@@ -46,14 +47,11 @@ class SyncGate extends React.Component {
   }
 
   render() {
-    const entryArrays = Object.keys(this.props.entries).map((key) => {
-      return this.props.entries[key].value;
-    });
-
+    const entryArrays = this.props.entries;
     const journals = this.props.journals.value;
 
     if ((journals === null) ||
-      (entryArrays.length === 0) || !entryArrays.every((x: any) => (x !== null))) {
+      (entryArrays.size === 0) || !entryArrays.every((x: any) => (x.value !== null))) {
       return (<LoadingIndicator />);
     }
 
diff --git a/src/etesync-helpers.tsx b/src/etesync-helpers.tsx
index 17384ac..c3dd3be 100644
--- a/src/etesync-helpers.tsx
+++ b/src/etesync-helpers.tsx
@@ -1,3 +1,5 @@
+import { List } from 'immutable';
+
 import * as EteSync from './api/EteSync';
 
 import { CredentialsData, createEntries } from './store';
@@ -5,7 +7,7 @@ import { CredentialsData, createEntries } from './store';
 export function createJournalEntry(
   etesync: CredentialsData,
   journal: EteSync.Journal,
-  existingEntries: Array<EteSync.Entry>,
+  existingEntries: List<EteSync.Entry>,
   action: EteSync.SyncEntryAction,
   content: string) {
 
@@ -18,8 +20,9 @@ export function createJournalEntry(
   let prevUid: string | null = null;
 
   const entries = existingEntries;
-  if (entries.length > 0) {
-    prevUid = entries[entries.length - 1].uid;
+  const last = entries.last();
+  if (last) {
+    prevUid = last.uid;
   }
 
   const cryptoManager = new EteSync.CryptoManager(derived, journal.uid, journal.version);
diff --git a/src/journal-processors.tsx b/src/journal-processors.tsx
index 8c47c8a..3b3d6a9 100644
--- a/src/journal-processors.tsx
+++ b/src/journal-processors.tsx
@@ -1,10 +1,12 @@
+import { List } from 'immutable';
+
 import * as ICAL from 'ical.js';
 
 import { EventType, ContactType } from './pim-types';
 
 import * as EteSync from './api/EteSync';
 
-export function syncEntriesToItemMap(collection: EteSync.CollectionInfo, entries: EteSync.SyncEntry[]) {
+export function syncEntriesToItemMap(collection: EteSync.CollectionInfo, entries: List<EteSync.SyncEntry>) {
   let items: {[key: string]: ContactType} = {};
 
   for (const syncEntry of entries) {
@@ -47,7 +49,7 @@ function colorIntToHtml(color: number) {
     ((alpha > 0) ? toHex(alpha) : '');
 }
 
-export function syncEntriesToCalendarItemMap(collection: EteSync.CollectionInfo, entries: EteSync.SyncEntry[]) {
+export function syncEntriesToCalendarItemMap(collection: EteSync.CollectionInfo, entries: List<EteSync.SyncEntry>) {
   let items: {[key: string]: EventType} = {};
 
   const color = colorIntToHtml(collection.color);
diff --git a/src/store.test.tsx b/src/store.test.tsx
index c6a0e43..bc88d1a 100644
--- a/src/store.test.tsx
+++ b/src/store.test.tsx
@@ -1,10 +1,12 @@
-import { entries, createEntries, fetchEntries } from './store';
+import { entries, createEntries, fetchEntries, EntriesTypeImmutable } from './store';
+
+import { Map } from 'immutable';
 
 import * as EteSync from './api/EteSync';
 
 it('Entries reducer', () => {
   const jId = '24324324324';
-  let state = {};
+  let state = Map({}) as EntriesTypeImmutable;
 
   let entry = new EteSync.Entry();
   entry.deserialize({
@@ -18,21 +20,30 @@ it('Entries reducer', () => {
     payload: [entry],
   };
 
+  let journal;
+  let entry2;
+
   state = entries(state, action as any);
-  expect(state[jId].value[0].serialize()).toEqual(entry.serialize());
+  journal = state.get(jId) as any;
+  entry2 = journal.value.get(0);
+  expect(entry2.serialize()).toEqual(entry.serialize());
 
   // We replace if there's no prevUid
   state = entries(state, action as any);
-  expect(state[jId].value[0].serialize()).toEqual(entry.serialize());
-  expect(state[jId].value.length).toBe(1);
+  journal = state.get(jId) as any;
+  entry2 = journal.value.get(0);
+  expect(entry2.serialize()).toEqual(entry.serialize());
+  expect(journal.value.size).toBe(1);
 
   // We extend if prevUid is set
   action.meta.prevUid = entry.uid;
   state = entries(state, action as any);
-  expect(state[jId].value.length).toBe(2);
+  journal = state.get(jId) as any;
+  expect(journal.value.size).toBe(2);
 
   // Creating entries should also work the same
   action.type = createEntries.toString();
   state = entries(state, action as any);
-  expect(state[jId].value.length).toBe(3);
+  journal = state.get(jId) as any;
+  expect(journal.value.size).toBe(3);
 });
diff --git a/src/store.tsx b/src/store.tsx
index 3b67d95..c28c9a7 100644
--- a/src/store.tsx
+++ b/src/store.tsx
@@ -6,11 +6,13 @@ import session from 'redux-persist/lib/storage/session';
 import thunkMiddleware from 'redux-thunk';
 import { createLogger } from 'redux-logger';
 
+import { List, Map, Record } from 'immutable';
+
 import promiseMiddleware from './promise-middleware';
 
 import * as EteSync from './api/EteSync';
 
-export interface FetchType<T> {
+interface FetchTypeInterface<T> {
   value: T | null;
   fetching?: boolean;
   error?: Error;
@@ -22,15 +24,27 @@ export interface CredentialsData {
   encryptionKey: string;
 }
 
+type FetchType<T> = FetchTypeInterface<T>;
+
+function fetchTypeRecord<T>() {
+  return Record<FetchTypeInterface<T>>({
+    value: null as T | null,
+  });
+}
+
 export type CredentialsType = FetchType<CredentialsData>;
 
-export type JournalsData = Array<EteSync.Journal>;
+export type JournalsData = List<EteSync.Journal>;
 
+const JournalsFetchRecord = fetchTypeRecord<JournalsData>();
 export type JournalsType = FetchType<JournalsData>;
 
-export type EntriesData = Array<EteSync.Entry>;
+export type EntriesData = List<EteSync.Entry>;
 
-export type EntriesType = {[key: string]: FetchType<EntriesData>};
+const EntriesFetchRecord = fetchTypeRecord<EntriesData>();
+
+export type EntriesTypeImmutable = Map<string, Record<FetchType<EntriesData>>>;
+export type EntriesType = Map<string, FetchType<EntriesData>>;
 
 export interface StoreState {
   fetchCount: number;
@@ -41,7 +55,7 @@ export interface StoreState {
   };
 }
 
-function fetchTypeIdentityReducer(state: FetchType<any> = {value: null}, action: any, extend: boolean = false) {
+function credentialsIdentityReducer(state: CredentialsType = {value: null}, action: any, extend: boolean = false) {
   if (action.error) {
     return {
       value: null,
@@ -50,18 +64,32 @@ function fetchTypeIdentityReducer(state: FetchType<any> = {value: null}, action:
   } else {
     const fetching = (action.payload === undefined) ? true : undefined;
     const payload = (action.payload === undefined) ? null : action.payload;
-    let value = state.value;
+    let value = payload;
+    return {
+      fetching,
+      value,
+    };
+  }
+}
+
+function fetchTypeIdentityReducer(
+  state: Record<FetchType<any>> = fetchTypeRecord<any>()(), action: any, extend: boolean = false) {
+  if (action.error) {
+    return state.set('value', null).set('error', action.payload);
+  } else {
+    const fetching = (action.payload === undefined) ? true : undefined;
+    const payload = (action.payload === undefined) ? null : action.payload;
+    let value = state.get('value', null);
     if (extend && (value !== null)) {
       if (payload !== null) {
         value = value.concat(payload);
       }
+    } else if (payload !== null) {
+      value = List(payload);
     } else {
-      value = payload;
+      value = null;
     }
-    return {
-      fetching,
-      value,
-    };
+    return state.set('value', value).set('fetching', fetching);
   }
 }
 
@@ -131,7 +159,7 @@ export const { fetchEntries, createEntries } = createActions({
 
 const credentials = handleActions(
   {
-    [fetchCredentials.toString()]: fetchTypeIdentityReducer,
+    [fetchCredentials.toString()]: credentialsIdentityReducer,
     [logout.toString()]: (state: CredentialsType, action: any) => {
       return {out: true, value: null};
     },
@@ -141,20 +169,19 @@ const credentials = handleActions(
 
 export const entries = handleAction(
   combineActions(fetchEntries, createEntries),
-  (state: EntriesType, action: any) => {
-    const prevState = state[action.meta.journal];
+  (state: EntriesTypeImmutable, action: any) => {
+    const prevState = state.get(action.meta.journal);
     const extend = action.meta.prevUid != null;
-    return { ...state,
-      [action.meta.journal]: fetchTypeIdentityReducer(prevState, action, extend)
-    };
+    return state.set(action.meta.journal,
+                     fetchTypeIdentityReducer(prevState, action, extend));
   },
-  {}
+  Map({})
 );
 
 const journals = handleAction(
   fetchJournals,
   fetchTypeIdentityReducer,
-  {value: null}
+  JournalsFetchRecord(),
 );
 
 const fetchCount = handleAction(
@@ -184,7 +211,7 @@ const journalsSerialize = (state: JournalsData) => {
     return null;
   }
 
-  return state.map((x) => x.serialize());
+  return state.map((x) => x.serialize()).toJS();
 };
 
 const journalsDeserialize = (state: EteSync.JournalJson[]) => {
@@ -192,53 +219,74 @@ const journalsDeserialize = (state: EteSync.JournalJson[]) => {
     return null;
   }
 
-  return state.map((x: any) => {
+  return List(state.map((x: any) => {
     let ret = new EteSync.Journal(x.version);
     ret.deserialize(x);
     return ret;
-  });
-};
-
-const cacheJournalsPersistConfig = {
-  key: 'journals',
-  storage: localforage,
-  transforms: [createTransform(journalsSerialize, journalsDeserialize)],
-  whitelist: ['value'],
+  }));
 };
 
-const entriesSerialize = (state: FetchType<EntriesData>, key: string) => {
+const entriesSerialize = (state: FetchType<EntriesData>) => {
   if ((state === null) || (state.value == null)) {
     return null;
   }
 
-  return state.value.map((x) => x.serialize());
+  return state.value.map((x) => x.serialize()).toJS();
 };
 
-const entriesDeserialize = (state: EteSync.EntryJson[], key: string): FetchType<EntriesData> => {
+const entriesDeserialize = (state: EteSync.EntryJson[]): FetchType<EntriesData> => {
   if (state === null) {
-    return {value: null};
+    return EntriesFetchRecord({value: null});
   }
 
-  return {value: state.map((x: any) => {
+  return EntriesFetchRecord({value: List(state.map((x: any) => {
     let ret = new EteSync.Entry();
     ret.deserialize(x);
     return ret;
-  })};
+  }))});
+};
+
+const cacheSerialize = (state: any, key: string) => {
+  if (key === 'entries') {
+    let ret = {};
+    state.forEach((value: FetchType<EntriesData>, mapKey: string) => {
+      ret[mapKey] = entriesSerialize(value);
+    });
+    return ret;
+  } else if (key === 'journals') {
+    return journalsSerialize(state.value);
+  }
+
+  return state;
+};
+
+const cacheDeserialize = (state: any, key: string) => {
+  if (key === 'entries') {
+    let ret = {};
+    Object.keys(state).forEach((mapKey) => {
+      ret[mapKey] = entriesDeserialize(state[mapKey]);
+    });
+    return Map(ret);
+  } else if (key === 'journals') {
+    return JournalsFetchRecord({value: journalsDeserialize(state)});
+  }
+
+  return state;
 };
 
-const cacheEntriesPersistConfig = {
-  key: 'entries',
+const cachePersistConfig = {
+  key: 'cache',
   storage: localforage,
-  transforms: [createTransform(entriesSerialize, entriesDeserialize)],
+  transforms: [createTransform(cacheSerialize, cacheDeserialize)],
 };
 
 const reducers = combineReducers({
   fetchCount,
   credentials: persistReducer(credentialsPersistConfig, credentials),
-  cache: combineReducers({
-    journals: persistReducer(cacheJournalsPersistConfig, journals),
-    entries: persistReducer(cacheEntriesPersistConfig, entries),
-  })
+  cache: persistReducer(cachePersistConfig, combineReducers({
+    entries,
+    journals,
+  })),
 });
 
 let middleware = [