diff --git a/changelog.d/11191.bugfix b/changelog.d/11191.bugfix
new file mode 100644
index 000000000..9104db7f0
--- /dev/null
+++ b/changelog.d/11191.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in Synapse 1.45.0 which prevented the `synapse_review_recent_signups` script from running. Contributed by @samuel-p.
diff --git a/synapse/_scripts/review_recent_signups.py b/synapse/_scripts/review_recent_signups.py
index 9de913db8..8e66a3842 100644
--- a/synapse/_scripts/review_recent_signups.py
+++ b/synapse/_scripts/review_recent_signups.py
@@ -20,7 +20,12 @@ from typing import List
 
 import attr
 
-from synapse.config._base import RootConfig, find_config_files, read_config_files
+from synapse.config._base import (
+    Config,
+    RootConfig,
+    find_config_files,
+    read_config_files,
+)
 from synapse.config.database import DatabaseConfig
 from synapse.storage.database import DatabasePool, LoggingTransaction, make_conn
 from synapse.storage.engines import create_engine
@@ -126,7 +131,7 @@ def main():
         config_dict,
     )
 
-    since_ms = time.time() * 1000 - config.parse_duration(config_args.since)
+    since_ms = time.time() * 1000 - Config.parse_duration(config_args.since)
     exclude_users_with_email = config_args.exclude_emails
     include_context = not config_args.only_users