diff --git a/puppet/zulip/files/supervisor/conf.d/thumbor.conf b/puppet/zulip/files/supervisor/conf.d/thumbor.conf
index 637d7e17dc..d6b1706c66 100644
--- a/puppet/zulip/files/supervisor/conf.d/thumbor.conf
+++ b/puppet/zulip/files/supervisor/conf.d/thumbor.conf
@@ -1,5 +1,5 @@
 [program:zulip-thumbor]
-command=/home/zulip/deployments/current/zulip-thumbor-venv/bin/thumbor --port=9995 --conf=/home/zulip/deployments/current/zthumbor/thumbor.conf
+command=/home/zulip/deployments/current/zulip-thumbor-venv/bin/thumbor --port=9995 --conf=/home/zulip/deployments/current/zthumbor/thumbor_settings.py
 user=zulip
 directory=/home/zulip/deployments/current/
 autostart=true
diff --git a/tools/run-dev.py b/tools/run-dev.py
index 0ad5d91eaf..0f92d381b3 100755
--- a/tools/run-dev.py
+++ b/tools/run-dev.py
@@ -151,7 +151,7 @@ def server_processes() -> List[List[str]]:
         ['env', 'PGHOST=127.0.0.1',  # Force password authentication using .pgpass
          './puppet/zulip/files/postgresql/process_fts_updates', '--quiet'],
         ['./manage.py', 'deliver_scheduled_messages'],
-        ['/srv/zulip-thumbor-venv/bin/thumbor', '-c', './zthumbor/thumbor.conf',
+        ['/srv/zulip-thumbor-venv/bin/thumbor', '-c', './zthumbor/thumbor_settings.py',
          '-p', f'{thumbor_port}'],
     ]
 
diff --git a/zthumbor/thumbor.conf b/zthumbor/thumbor_settings.py
similarity index 100%
rename from zthumbor/thumbor.conf
rename to zthumbor/thumbor_settings.py