diff --git a/synapse/replication/slave/storage/appservice.py b/synapse/replication/slave/storage/appservice.py
index 73048327c57dc40b07e68e2f21f01eb241f1179c..0d3f31a50c2477ce8c4851f9f117415ba6a21f26 100644
--- a/synapse/replication/slave/storage/appservice.py
+++ b/synapse/replication/slave/storage/appservice.py
@@ -16,6 +16,7 @@
 from ._base import BaseSlavedStore
 from synapse.storage import DataStore
 from synapse.config.appservice import load_appservices
+from synapse.storage.appservice import _make_exclusive_regex
 
 
 class SlavedApplicationServiceStore(BaseSlavedStore):
@@ -25,6 +26,7 @@ class SlavedApplicationServiceStore(BaseSlavedStore):
             hs.config.server_name,
             hs.config.app_service_config_files
         )
+        self.exclusive_user_regex = _make_exclusive_regex(self.services_cache)
 
     get_app_service_by_token = DataStore.get_app_service_by_token.__func__
     get_app_service_by_user_id = DataStore.get_app_service_by_user_id.__func__
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 532df736a5fd916fab8ae6679eccc4b9e8c54fb4..c63935cb07c30d30599a18952ba25c120877312b 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -27,6 +27,25 @@ from ._base import SQLBaseStore
 logger = logging.getLogger(__name__)
 
 
+def _make_exclusive_regex(services_cache):
+    # We precompie a regex constructed from all the regexes that the AS's
+    # have registered for exclusive users.
+    exclusive_user_regexes = [
+        regex.pattern
+        for service in services_cache
+        for regex in service.get_exlusive_user_regexes()
+    ]
+    if exclusive_user_regexes:
+        exclusive_user_regex = "|".join("(" + r + ")" for r in exclusive_user_regexes)
+        exclusive_user_regex = re.compile(exclusive_user_regex)
+    else:
+        # We handle this case specially otherwise the constructed regex
+        # will always match
+        exclusive_user_regex = None
+
+    return exclusive_user_regex
+
+
 class ApplicationServiceStore(SQLBaseStore):
 
     def __init__(self, hs):
@@ -36,21 +55,7 @@ class ApplicationServiceStore(SQLBaseStore):
             hs.hostname,
             hs.config.app_service_config_files
         )
-
-        # We precompie a regex constructed from all the regexes that the AS's
-        # have registered for exclusive users.
-        exclusive_user_regexes = [
-            regex.pattern
-            for service in self.services_cache
-            for regex in service.get_exlusive_user_regexes()
-        ]
-        if exclusive_user_regexes:
-            exclusive_user_regex = "|".join("(" + r + ")" for r in exclusive_user_regexes)
-            self.exclusive_user_regex = re.compile(exclusive_user_regex)
-        else:
-            # We handle this case specially otherwise the constructed regex
-            # will always match
-            self.exclusive_user_regex = None
+        self.exclusive_user_regex = _make_exclusive_regex(self.services_cache)
 
     def get_app_services(self):
         return self.services_cache