diff --git a/MultiServer.py b/MultiServer.py
index f9ed34e2..f465b739 100644
--- a/MultiServer.py
+++ b/MultiServer.py
@@ -66,9 +66,13 @@ def pop_from_container(container, value):
     return container
 
 
-def update_dict(dictionary, entries):
-    dictionary.update(entries)
-    return dictionary
+def update_container_unique(container, entries):
+    if isinstance(container, list):
+        existing_container_as_set = set(container)
+        container.extend([entry for entry in entries if entry not in existing_container_as_set])
+    else:
+        container.update(entries)
+    return container
 
 
 def queue_gc():
@@ -109,7 +113,7 @@ modify_functions = {
     # lists/dicts:
     "remove": remove_from_list,
     "pop": pop_from_container,
-    "update": update_dict,
+    "update": update_container_unique,
 }
 
 
diff --git a/docs/network protocol.md b/docs/network protocol.md
index 70c66543..6688c101 100644
--- a/docs/network protocol.md	
+++ b/docs/network protocol.md	
@@ -470,7 +470,7 @@ The following operations can be applied to a datastorage key
 | right_shift | Applies a bitwise right-shift to the current value of the key by `value`. |
 | remove | List only: removes the first instance of `value` found in the list. |
 | pop | List or Dict: for lists it will remove the index of the `value` given. for dicts it removes the element with the specified key of `value`. |
-| update | Dict only: Updates the dictionary with the specified elements given in `value` creating new keys, or updating old ones if they previously existed. |
+| update | List or Dict: Adds the elements of `value` to the container if they weren't already present. In the case of a Dict, already present keys will have their corresponding values updated. |
 
 ### SetNotify
 Used to register your current session for receiving all [SetReply](#SetReply) packages of certain keys to allow your client to keep track of changes.