diff --git a/docs/source/getting-started/services-basics.md b/docs/source/getting-started/services-basics.md
index 9b5aa7b1..e9e399e2 100644
--- a/docs/source/getting-started/services-basics.md
+++ b/docs/source/getting-started/services-basics.md
@@ -88,7 +88,7 @@ c.JupyterHub.services = [
     {
         'name': 'cull-idle',
         'admin': True,
-        'command': 'python cull_idle_servers.py --timeout=3600'.split(),
+        'command': 'python3 cull_idle_servers.py --timeout=3600'.split(),
     }
 ]
 ```
@@ -115,7 +115,7 @@ variable. Run `cull_idle_servers.py` manually.
 
 ```bash
     export JUPYTERHUB_API_TOKEN='token'
-    python cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
+    python3 cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
 ```
 
 [cull_idle_servers]: https://github.com/jupyterhub/jupyterhub/blob/master/examples/cull-idle/cull_idle_servers.py
diff --git a/examples/cull-idle/README.md b/examples/cull-idle/README.md
index ac775a58..c02320f2 100644
--- a/examples/cull-idle/README.md
+++ b/examples/cull-idle/README.md
@@ -15,7 +15,7 @@ c.JupyterHub.services = [
     {
         'name': 'cull-idle',
         'admin': True,
-        'command': 'python cull_idle_servers.py --timeout=3600'.split(),
+        'command': 'python3 cull_idle_servers.py --timeout=3600'.split(),
     }
 ]
 ```
@@ -37,5 +37,5 @@ variable. Run `cull_idle_servers.py` manually.
 
 ```bash
     export JUPYTERHUB_API_TOKEN=`jupyterhub token`
-    python cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
+    python3 cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
 ```
diff --git a/examples/cull-idle/cull_idle_servers.py b/examples/cull-idle/cull_idle_servers.py
index 258832e5..7549f1d2 100755
--- a/examples/cull-idle/cull_idle_servers.py
+++ b/examples/cull-idle/cull_idle_servers.py
@@ -16,14 +16,14 @@ You can run this as a service managed by JupyterHub with this in your config::
         {
             'name': 'cull-idle',
             'admin': True,
-            'command': 'python cull_idle_servers.py --timeout=3600'.split(),
+            'command': 'python3 cull_idle_servers.py --timeout=3600'.split(),
         }
     ]
 
 Or run it manually by generating an API token and storing it in `JUPYTERHUB_API_TOKEN`:
 
     export JUPYTERHUB_API_TOKEN=`jupyterhub token`
-    python cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
+    python3 cull_idle_servers.py [--timeout=900] [--url=http://127.0.0.1:8081/hub/api]
 """
 
 from datetime import datetime, timezone
diff --git a/examples/cull-idle/jupyterhub_config.py b/examples/cull-idle/jupyterhub_config.py
index 2de8f424..f8a6bf52 100644
--- a/examples/cull-idle/jupyterhub_config.py
+++ b/examples/cull-idle/jupyterhub_config.py
@@ -3,6 +3,6 @@ c.JupyterHub.services = [
     {
         'name': 'cull-idle',
         'admin': True,
-        'command': 'python cull_idle_servers.py --timeout=3600'.split(),
+        'command': 'python3 cull_idle_servers.py --timeout=3600'.split(),
     }
 ]