diff --git a/lib/ace/keyboard/emacs.js b/lib/ace/keyboard/emacs.js
index f0df7d87..25f22a52 100644
--- a/lib/ace/keyboard/emacs.js
+++ b/lib/ace/keyboard/emacs.js
@@ -429,7 +429,13 @@ exports.handler.addCommands({
     },
     exchangePointAndMark: {
         exec: function(editor) {
-            var range = editor.selection.getRange();
+            var sel = editor.selection;
+            var range = sel.getRange();
+            if (range.isEmpty()) {
+                var lastMark = editor.getLastEmacsMark();
+                sel.selectToPosition(lastMark);
+                return;
+            }
             editor.selection.setSelectionRange(range, !editor.selection.isBackwards());
         },
         readonly: true,