diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index f8266d1c816bc36ce07f9f9472024f82ca5fc6c3..e3da45b41669f96d92f8c2a2017358b51c8a7edf 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -209,7 +209,7 @@ class Auth(object):
             )[0]
             if user and access_token and ip_addr:
                 self.store.insert_client_ip(
-                    user=user,
+                    user_id=user.to_string(),
                     access_token=access_token,
                     ip=ip_addr,
                     user_agent=user_agent,
diff --git a/synapse/replication/slave/storage/client_ips.py b/synapse/replication/slave/storage/client_ips.py
index 65250285e823299809929ffbc86af853e68d28ac..352c9a2aa80e904cc53b69d9a097576123c159b9 100644
--- a/synapse/replication/slave/storage/client_ips.py
+++ b/synapse/replication/slave/storage/client_ips.py
@@ -29,9 +29,8 @@ class SlavedClientIpStore(BaseSlavedStore):
             max_entries=50000 * CACHE_SIZE_FACTOR,
         )
 
-    def insert_client_ip(self, user, access_token, ip, user_agent, device_id):
+    def insert_client_ip(self, user_id, access_token, ip, user_agent, device_id):
         now = int(self._clock.time_msec())
-        user_id = user.to_string()
         key = (user_id, access_token, ip)
 
         try:
diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py
index a009214e4372ea0385e239b4ae02efd6ab9d04a5..171227cce2ef4139bae845a6a307a21f3e0faae7 100644
--- a/synapse/replication/tcp/commands.py
+++ b/synapse/replication/tcp/commands.py
@@ -323,14 +323,18 @@ class UserIpCommand(Command):
 
     @classmethod
     def from_line(cls, line):
-        user_id, access_token, ip, device_id, last_seen, user_agent = line.split(" ", 5)
+        user_id, jsn = line.split(" ", 1)
 
-        return cls(user_id, access_token, ip, user_agent, device_id, int(last_seen))
+        access_token, ip, user_agent, device_id, last_seen = json.loads(jsn)
+
+        return cls(
+            user_id, access_token, ip, user_agent, device_id, last_seen
+        )
 
     def to_line(self):
-        return " ".join((
-            self.user_id, self.access_token, self.ip, self.device_id,
-            str(self.last_seen), self.user_agent,
+        return self.user_id + " " + json.dumps((
+            self.access_token, self.ip, self.user_agent, self.device_id,
+            self.last_seen,
         ))
 
 
diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index fc468ea18532ae7f8b35fbe8b6a07adc64ab68a3..3c95e90eca40b84d8315f7d85bfb3785caa25a95 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -56,9 +56,11 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
         )
         reactor.addSystemEventTrigger("before", "shutdown", self._update_client_ips_batch)
 
-    def insert_client_ip(self, user, access_token, ip, user_agent, device_id):
-        now = int(self._clock.time_msec())
-        key = (user.to_string(), access_token, ip)
+    def insert_client_ip(self, user_id, access_token, ip, user_agent, device_id,
+                         now=None):
+        if not now:
+            now = int(self._clock.time_msec())
+        key = (user_id, access_token, ip)
 
         try:
             last_seen = self.client_ip_last_seen.get(key)
diff --git a/tests/handlers/test_device.py b/tests/handlers/test_device.py
index 2eaaa8253ccbc7d67e608024feef5be5c056fe28..778ff2f6e92eeba6f3c0ad9da432dcff284db988 100644
--- a/tests/handlers/test_device.py
+++ b/tests/handlers/test_device.py
@@ -19,7 +19,6 @@ import synapse.api.errors
 import synapse.handlers.device
 
 import synapse.storage
-from synapse import types
 from tests import unittest, utils
 
 user1 = "@boris:aaa"
@@ -179,6 +178,6 @@ class DeviceTestCase(unittest.TestCase):
 
         if ip is not None:
             yield self.store.insert_client_ip(
-                types.UserID.from_string(user_id),
+                user_id,
                 access_token, ip, "user_agent", device_id)
             self.clock.advance_time(1000)
diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py
index 03df697575bec2c70c9663657e7ae96366ffaa67..bd6fda6cb12f9fb646271709fb95fc79e16429c8 100644
--- a/tests/storage/test_client_ips.py
+++ b/tests/storage/test_client_ips.py
@@ -15,9 +15,6 @@
 
 from twisted.internet import defer
 
-import synapse.server
-import synapse.storage
-import synapse.types
 import tests.unittest
 import tests.utils
 
@@ -39,7 +36,7 @@ class ClientIpStoreTestCase(tests.unittest.TestCase):
         self.clock.now = 12345678
         user_id = "@user:id"
         yield self.store.insert_client_ip(
-            synapse.types.UserID.from_string(user_id),
+            user_id,
             "access_token", "ip", "user_agent", "device_id",
         )