diff --git a/Map.js b/Map.js
index ff52e56..08ee2b4 100644
--- a/Map.js
+++ b/Map.js
@@ -40,6 +40,20 @@ object.Mixin('MapProtoMixin', 'soft', {
 					del(k)
 					set(k, v) } }.bind(this))
 		return this },
+
+	replaceKey: function(old, key, ordered=true){
+		if(!this.has(old)){
+			return this }
+		if(ordered){
+			var order = [...this.keys()]
+			order[order.lastIndexOf(old)] = key }
+		// replace...
+		var value = this.get(old)
+		this.delete(old)
+		this.set(key, value)
+		ordered
+			&& this.sort(order)
+		return this },
 })
 
 
diff --git a/README.md b/README.md
index d6512d9..f3376e0 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,7 @@ Library of JavaScript type extensions, types and utilities.
       - [`<array>.CHUNK_SIZE`](#arraychunk_size)
       - [`<array>.mapChunks(..)` / `<array>.filterChunks(..)` / `<array>.reduceChunks(..)`](#arraymapchunks--arrayfilterchunks--arrayreducechunks)
   - [`Map`](#map)
+    - [`<map>.replaceKey(..)`](#mapreplacekey)
     - [`<map>.sort(..)`](#mapsort)
   - [`Set`](#set)
     - [`<set>.replace(..)`](#setreplace)
@@ -858,6 +859,24 @@ require('ig-types/Map')
 ```
 
 
+### `<map>.replaceKey(..)`
+
+Replace key in map retaining item order
+```bnf
+<map>.replaceKey(<old>, <new>)
+    -> <map>
+```
+
+Replace the key without sorting
+```bnf
+<map>.replaceKey(<old>, <new>, false)
+    -> <map>
+```
+
+Note that when sorting large maps this can get expensive.
+
+
+
 ### `<map>.sort(..)`
 
 Sort `<map>` keys in-place
diff --git a/package.json b/package.json
index c0fad7f..f1d5205 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ig-types",
-  "version": "6.6.0",
+  "version": "6.7.0",
   "description": "Generic JavaScript types and type extensions...",
   "main": "main.js",
   "scripts": {