diff --git a/matrix/buffer.py b/matrix/buffer.py
index a796c44..b6a5e52 100644
--- a/matrix/buffer.py
+++ b/matrix/buffer.py
@@ -20,6 +20,7 @@ from __future__ import unicode_literals
 import time
 from builtins import super
 from functools import partial
+from collections import deque
 from typing import Dict, List, NamedTuple, Optional, Set
 from uuid import UUID
 
@@ -816,6 +817,7 @@ class RoomBuffer(object):
 
         self.sent_messages_queue = dict()  # type: Dict[UUID, OwnMessage]
         self.printed_before_ack_queue = list()  # type: List[UUID]
+        self.undecrypted_events = deque(maxlen=5000)
 
         buffer_name = "{}.{}".format(server_name, room.room_id)
 
@@ -1300,6 +1302,8 @@ class RoomBuffer(object):
                 self.get_event_tags(event) + [session_id_tag]
             )
 
+            self.undecrypted_events.append(event)
+
         else:
             W.prnt(
                 "", "Unhandled event of type {}.".format(type(event).__name__)
@@ -1384,6 +1388,43 @@ class RoomBuffer(object):
             new_tags.append(SCRIPT_NAME + "_id_" + new_message.event_id)
             line.tags = new_tags
 
+    def replace_undecrypted_line(self, event):
+        """Find a undecrypted message in the buffer and replace it with the now
+        decrypted event."""
+        # TODO different messages need different formatting
+        # To implement this, refactor out the different formatting code
+        # snippets to a Formatter class and reuse them here.
+        if not isinstance(event, RoomMessageText):
+            return
+
+        def predicate(event_id, line):
+            event_tag = SCRIPT_NAME + "_id_{}".format(event_id)
+            if event_tag in line.tags:
+                return True
+            return False
+
+        lines = self.weechat_buffer.find_lines(
+            partial(predicate, event.event_id)
+        )
+
+        if not lines:
+            return
+
+        formatted = None
+        if event.formatted_body:
+            formatted = Formatted.from_html(event.formatted_body)
+
+        data = formatted.to_weechat() if formatted else event.body
+        # TODO this isn't right if the data has multiple lines, that is
+        # everything is printed on a signle line and newlines are shown as a
+        # space.
+        # Weechat should support deleting lines and printing new ones at an
+        # arbitrary position.
+        # To implement this without weechat support either only handle single
+        # line messages or edit the first line in place, print new ones at the
+        # bottom and sort the buffer lines.
+        lines[0].message = data
+
     def old_redacted(self, event):
         tags = [
             SCRIPT_NAME + "_message",
diff --git a/matrix/server.py b/matrix/server.py
index d4e2d22..2cdd3ee 100644
--- a/matrix/server.py
+++ b/matrix/server.py
@@ -957,6 +957,28 @@ class MatrixServer(object):
                                 "matrix_load_users_cb", self.name)
             self.lazy_load_hook = hook
 
+    def decrypt_printed_messages(self, key_event):
+        """Decrypt already printed messages and send them to the buffer"""
+        try:
+            room_buffer = self.find_room_from_id(key_event.room_id)
+        except KeyError:
+            return
+
+        decrypted_events = []
+
+        for undecrypted_event in room_buffer.undecrypted_events:
+            if undecrypted_event.session_id != key_event.session_id:
+                continue
+
+            event = self.client.decrypt_event(undecrypted_event)
+            if event:
+                decrypted_events.append((undecrypted_event, event))
+
+        for event_pair in decrypted_events:
+            undecrypted_event, event = event_pair
+            room_buffer.undecrypted_events.remove(undecrypted_event)
+            room_buffer.replace_undecrypted_line(event)
+
     def _handle_sync(self, response):
         # we got the same batch again, nothing to do
         if self.next_batch == response.next_batch:
@@ -979,6 +1001,10 @@ class MatrixServer(object):
             }
             W.hook_hsignal_send("matrix_room_key_received", message)
 
+            # TODO try to decrypt some cached undecrypted messages with the
+            # new key
+            # self.decrypt_printed_messages(event)
+
         # Full sync response handle everything.
         if isinstance(response, SyncResponse):
             if self.client.should_upload_keys: