diff --git a/matrix/encryption.py b/matrix/encryption.py
index ea731d0..d5f6e08 100644
--- a/matrix/encryption.py
+++ b/matrix/encryption.py
@@ -409,9 +409,10 @@ class Olm():
                     }
                 }
 
-                to_device_dict["messages"][user] = {
-                    key.device_id: olm_dict
-                }
+                if user not in to_device_dict["messages"]:
+                    to_device_dict["messages"][user] = {}
+
+                to_device_dict["messages"][user][key.device_id] = olm_dict
 
         return to_device_dict