diff --git a/lib/datastore.js b/lib/datastore.js
index 11050b9..1a6aa48 100755
--- a/lib/datastore.js
+++ b/lib/datastore.js
@@ -431,7 +431,7 @@ class Datastore extends EventEmitter {
   /**
    * Callback version of {@link Datastore#ensureIndex}.
    * @param {object} options
-   * @param {string} options.fieldName
+   * @param {string|string[]} options.fieldName
    * @param {boolean} [options.unique = false]
    * @param {boolean} [options.sparse = false]
    * @param {number} [options.expireAfterSeconds]
@@ -448,7 +448,7 @@ class Datastore extends EventEmitter {
    * This function acts synchronously on the indexes, however the persistence of the indexes is deferred with the
    * executor.
    * @param {object} options
-   * @param {string} options.fieldName Name of the field to index. Use the dot notation to index a field in a nested
+   * @param {string|string[]} options.fieldName Name of the field to index. Use the dot notation to index a field in a nested
    * document. For a compound index, use an array of field names. Using a comma in a field name is not permitted.
    * @param {boolean} [options.unique = false] Enforce field uniqueness. Note that a unique index will raise an error
    * if you try to index two documents for which the field is not defined.
@@ -465,26 +465,32 @@ class Datastore extends EventEmitter {
       err.missingFieldName = true
       throw err
     }
-    if (Array.isArray(options.fieldName)) {
-      options.fieldName.sort()
-    }
-    if ([].concat(options.fieldName).some(field => field.includes(','))) {
+
+    const _fields = [].concat(options.fieldName).sort()
+
+    if (_fields.some(field => field.includes(','))) {
       throw new Error('Cannot use comma in index fieldName')
     }
-    if (this.indexes[options.fieldName]) return
 
-    this.indexes[options.fieldName] = new Index(options)
-    if (options.expireAfterSeconds !== undefined) this.ttlIndexes[options.fieldName] = options.expireAfterSeconds // With this implementation index creation is not necessary to ensure TTL but we stick with MongoDB's API here
+    const _options = {
+      ...options,
+      fieldName: _fields.join(',')
+    }
+
+    if (this.indexes[_options.fieldName]) return
+
+    this.indexes[_options.fieldName] = new Index(_options)
+    if (options.expireAfterSeconds !== undefined) this.ttlIndexes[_options.fieldName] = _options.expireAfterSeconds // With this implementation index creation is not necessary to ensure TTL but we stick with MongoDB's API here
 
     try {
-      this.indexes[options.fieldName].insert(this.getAllData())
+      this.indexes[_options.fieldName].insert(this.getAllData())
     } catch (e) {
-      delete this.indexes[options.fieldName]
+      delete this.indexes[_options.fieldName]
       throw e
     }
 
     // We may want to force all options to be persisted including defaults, not just the ones passed the index creation function
-    await this.executor.pushAsync(() => this.persistence.persistNewStateAsync([{ $$indexCreated: options }]), true)
+    await this.executor.pushAsync(() => this.persistence.persistNewStateAsync([{ $$indexCreated: _options }]), true)
   }
 
   /**
diff --git a/lib/indexes.js b/lib/indexes.js
index e1b5376..a0335ea 100755
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -38,16 +38,26 @@ class Index {
    * All methods on an index guarantee that either the whole operation was successful and the index changed
    * or the operation was unsuccessful and an error is thrown while the index is unchanged
    * @param {object} options
-   * @param {string} options.fieldName On which field should the index apply (can use dot notation to index on sub fields)
+   * @param {string} options.fieldName On which field should the index apply, can use dot notation to index on sub fields, can use comma-separated notation to use compound indexes
    * @param {boolean} [options.unique = false] Enforces a unique constraint
    * @param {boolean} [options.sparse = false] Allows a sparse index (we can have documents for which fieldName is `undefined`)
    */
   constructor (options) {
     /**
-     * On which field the index applies to (may use dot notation to index on sub fields).
+     * On which field the index applies to, can use dot notation to index on sub fields, can use comma-separated notation to use compound indexes.
      * @type {string}
      */
     this.fieldName = options.fieldName
+
+    if (typeof this.fieldName !== 'string') throw new Error('fieldName must be a string')
+
+    /**
+     * Internal property which is an Array representing the fieldName split with `,`, useful only for compound indexes.
+     * @type {string[]}
+     * @private
+     */
+    this._fields = this.fieldName.split(',')
+
     /**
      * Defines if the index enforces a unique constraint for this index.
      * @type {boolean}
@@ -99,7 +109,7 @@ class Index {
       return
     }
 
-    const key = model.getDotValues(doc, this.fieldName)
+    const key = model.getDotValues(doc, this._fields)
 
     // We don't index documents that don't contain the field if the index is sparse
     if ((key === undefined || (typeof key === 'object' && key !== null && Object.values(key).every(el => el === undefined))) && this.sparse) return
@@ -171,8 +181,7 @@ class Index {
       return
     }
 
-    const key = model.getDotValues(doc, this.fieldName)
-
+    const key = model.getDotValues(doc, this._fields)
     if (key === undefined && this.sparse) return
 
     if (!Array.isArray(key)) {
diff --git a/lib/model.js b/lib/model.js
index 9ba9724..ca9fd89 100755
--- a/lib/model.js
+++ b/lib/model.js
@@ -507,17 +507,14 @@ const getDotValue = (obj, field) => {
  * Get dot values for either a bunch of fields or just one.
  */
 const getDotValues = (obj, fields) => {
-  if (Array.isArray(fields)) {
+  if (!Array.isArray(fields)) throw new Error('fields must be an Array')
+  if (fields.length > 1) {
     const key = {}
-    const len = fields.length
-    for (let i = 0; i < len; i++) {
-      const field = fields[i]
+    for (const field of fields) {
       key[field] = getDotValue(obj, field)
     }
     return key
-  } else {
-    return getDotValue(obj, fields)
-  }
+  } else return getDotValue(obj, fields[0])
 }
 
 /**
diff --git a/test/db.async.test.js b/test/db.async.test.js
index a8ca172..45cb76e 100644
--- a/test/db.async.test.js
+++ b/test/db.async.test.js
@@ -1302,7 +1302,7 @@ describe('Database async', function () {
         assert.equal(d.indexes.z.tree.search('3')[0], d.getAllData()[2])
       })
 
-      it('ensureIndex can be called twice on the same field, the second call will ahve no effect', async () => {
+      it('ensureIndex can be called twice on the same field, the second call will have no effect', async () => {
         assert.equal(Object.keys(d.indexes).length, 1)
         assert.equal(Object.keys(d.indexes)[0], '_id')
 
@@ -1327,7 +1327,7 @@ describe('Database async', function () {
         assert.equal(d.indexes.planet.getAll().length, 2)
       })
 
-      it('ensureIndex can be called twice on the same compound field, the second call will ahve no effect', async () => {
+      it('ensureIndex can be called twice on the same compound field, the second call will have no effect', async () => {
         assert.equal(Object.keys(d.indexes).length, 1)
         assert.equal(Object.keys(d.indexes)[0], '_id')
 
@@ -1352,7 +1352,7 @@ describe('Database async', function () {
         assert.equal(d.indexes['planet,star'].getAll().length, 2)
       })
 
-      it('ensureIndex can be called twice on the same compound field with a different order, the second call will ahve no effect', async () => {
+      it('ensureIndex can be called twice on the same compound field with a different order, the second call will have no effect', async () => {
         assert.equal(Object.keys(d.indexes).length, 1)
         assert.equal(Object.keys(d.indexes)[0], '_id')
 
diff --git a/test/indexes.test.js b/test/indexes.test.js
index 3695204..7720619 100755
--- a/test/indexes.test.js
+++ b/test/indexes.test.js
@@ -30,7 +30,7 @@ describe('Indexes', function () {
     })
 
     it('Can insert pointers to documents in the index correctly when they have compound fields', function () {
-      const idx = new Index({ fieldName: ['tf', 'tg'] })
+      const idx = new Index({ fieldName: 'tf,tg' })
       const doc1 = { a: 5, tf: 'hello', tg: 'world' }
       const doc2 = { a: 8, tf: 'hello', tg: 'bloup' }
       const doc3 = { a: 2, tf: 'bloup', tg: 'bloup' }
@@ -81,7 +81,7 @@ describe('Indexes', function () {
     })
 
     it('Inserting twice for the same compound fieldName in a unique index will result in an error thrown', function () {
-      const idx = new Index({ fieldName: ['tf', 'tg'], unique: true })
+      const idx = new Index({ fieldName: 'tf,tg', unique: true })
       const doc1 = { a: 5, tf: 'hello', tg: 'world' }
 
       idx.insert(doc1)
@@ -90,7 +90,7 @@ describe('Indexes', function () {
     })
 
     it('Inserting twice for a compound fieldName the docs dont have with a unique and sparse index will not throw, since the docs will be non indexed', function () {
-      const idx = new Index({ fieldName: ['nope', 'nopeNope'], unique: true, sparse: true })
+      const idx = new Index({ fieldName: 'nope,nopeNope', unique: true, sparse: true })
       const doc1 = { a: 5, tf: 'hello' }
       const doc2 = { a: 5, tf: 'world' }
 
@@ -245,8 +245,8 @@ describe('Indexes', function () {
     }) // ==== End of 'Array fields' ==== //
 
     describe('Compound Indexes', function () {
-      it('Supports arrays of fieldNames', function () {
-        const idx = new Index({ fieldName: ['tf', 'tf2'] })
+      it('Supports field names separated by commas', function () {
+        const idx = new Index({ fieldName: 'tf,tf2' })
         const doc1 = { a: 5, tf: 'hello', tf2: 7 }
         const doc2 = { a: 8, tf: 'hello', tf2: 6 }
         const doc3 = { a: 2, tf: 'bloup', tf2: 3 }