diff --git a/tableaudocumentapi/multilookup_dict.py b/tableaudocumentapi/multilookup_dict.py
index 64b742a..6677b07 100644
--- a/tableaudocumentapi/multilookup_dict.py
+++ b/tableaudocumentapi/multilookup_dict.py
@@ -39,15 +39,25 @@ def _populate_indexes(self):
         self._indexes['alias'] = _build_index('alias', self)
         self._indexes['caption'] = _build_index('caption', self)
 
+    def _get_real_key(self, key):
+        if key in self._indexes['alias']:
+            return self._indexes['alias'][key]
+        if key in self._indexes['caption']:
+            return self._indexes['caption'][key]
+
+        return key
+
     def __setitem__(self, key, value):
+        real_key = self._get_real_key(key)
+
         alias = _resolve_value('alias', value)
         caption = _resolve_value('caption', value)
         if alias is not None:
-            self._indexes['alias'][alias] = key
+            self._indexes['alias'][alias] = real_key
         if caption is not None:
-            self._indexes['caption'][caption] = key
+            self._indexes['caption'][caption] = real_key
 
-        dict.__setitem__(self, key, value)
+        dict.__setitem__(self, real_key, value)
 
     def get(self, key, default_value=_no_default_value):
         try:
@@ -58,9 +68,5 @@ def get(self, key, default_value=_no_default_value):
             raise
 
     def __getitem__(self, key):
-        if key in self._indexes['alias']:
-            key = self._indexes['alias'][key]
-        elif key in self._indexes['caption']:
-            key = self._indexes['caption'][key]
-
-        return dict.__getitem__(self, key)
+        real_key = self._get_real_key(key)
+        return dict.__getitem__(self, real_key)
diff --git a/test/test_multidict.py b/test/test_multidict.py
index 0a78e9d..4544c49 100644
--- a/test/test_multidict.py
+++ b/test/test_multidict.py
@@ -61,3 +61,12 @@ def test_multilookupdict_get_returns_default_value(self):
     def test_multilookupdict_get_returns_value(self):
         actual = self.mld.get('baz')
         self.assertEqual(1, actual['value'])
+
+    def test_multilookupdict_can_set_item(self):
+        before = self.mld['baz']
+        self.mld['baz'] = 4
+        self.assertEqual(4, self.mld['baz'])
+
+    def test_multilookupdict_can_set_new_item(self):
+        self.mld['wakka'] = 1
+        self.assertEqual(1, self.mld['wakka'])