diff --git a/lib/indexes.js b/lib/indexes.js
index de22638..d8e4f84 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -33,6 +33,7 @@ function Index (options) {
 
 /**
  * Insert a new document in the index
+ * O(log(n))
  */
 Index.prototype.insert = function (doc) {
   var key = model.getDotValue(doc, this.fieldName);
@@ -49,6 +50,7 @@ Index.prototype.insert = function (doc) {
 
 /**
  * Remove a document from the index
+ * O(log(n))
  */
 Index.prototype.remove = function (doc) {
   var key = model.getDotValue(doc, this.fieldName);
@@ -62,6 +64,15 @@ Index.prototype.remove = function (doc) {
 };
 
 
+/**
+ * Update a document in the index
+ * O(log(n))
+ */
+Index.prototype.update = function (oldDoc, newDoc) {
+  this.remove(oldDoc);
+  this.insert(newDoc);
+};
+
 
 // Interface
 module.exports = Index;
diff --git a/test/indexes.test.js b/test/indexes.test.js
index 4b2eca0..8d09100 100644
--- a/test/indexes.test.js
+++ b/test/indexes.test.js
@@ -116,4 +116,34 @@ describe('Indexing', function () {
 
   });   // ==== End of 'Removal' ==== //
 
+
+  describe('Update', function () {
+
+    it('Can update a document whose key did or didnt change', function () {
+      var idx = new Index({ fieldName: 'tf' })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 8, tf: 'world' }
+        , doc3 = { a: 2, tf: 'bloup' }
+        , doc4 = { a: 23, tf: 'world' }
+        , doc5 = { a: 1, tf: 'changed' }
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.insert(doc3);
+      idx.tree.getNumberOfKeys().should.equal(3);
+      assert.deepEqual(idx.tree.search('world'), [doc2]);
+
+      idx.update(doc2, doc4);
+      idx.tree.getNumberOfKeys().should.equal(3);
+      assert.deepEqual(idx.tree.search('world'), [doc4]);
+
+      idx.update(doc1, doc5);
+      idx.tree.getNumberOfKeys().should.equal(3);
+      assert.deepEqual(idx.tree.search('hello'), []);
+      assert.deepEqual(idx.tree.search('changed'), [doc5]);
+    });
+
+  });   // ==== End of 'Update' ==== //
+
 });