diff --git a/ceo/cli/k8s.py b/ceo/cli/k8s.py
index 6094e4e..3594a21 100644
--- a/ceo/cli/k8s.py
+++ b/ceo/cli/k8s.py
@@ -31,6 +31,7 @@ def activate():
             os.rename(kubeconfig, kubeconfig_bak)
         with open(kubeconfig, 'w') as fo:
             fo.write(result['kubeconfig'])
+        os.chmod(kubeconfig, 0o600)
     except Exception:
         click.echo(traceback.format_exc())
         click.echo("We weren't able to write the kubeconfig file, so here it is.")