diff --git a/README.md b/README.md
index 4785900..19a008b 100644
--- a/README.md
+++ b/README.md
@@ -1469,6 +1469,32 @@ corresponding to when the API was available for use.
```
+#### `guiUndo`
+
+* Undo the last action / card; returns `true` if succeeded or `false` otherwise.
+
+
+ Sample request:
+
+ ```json
+ {
+ "action": "guiUndo",
+ "version": 6
+ }
+ ```
+
+
+
+ Sample result:
+
+ ```json
+ {
+ "result": true,
+ "error": null
+ }
+ ```
+
+
#### `guiDeckOverview`
* Opens the *Deck Overview* dialog for the deck with the given name; returns `true` if succeeded or `false` otherwise.