diff --git a/templates/prometheus.yml b/templates/prometheus.yml
index 666ad74..0af79cc 100644
--- a/templates/prometheus.yml
+++ b/templates/prometheus.yml
@@ -18,7 +18,7 @@ scrape_configs:
     static_configs:
       - targets: ['localhost:9090']
 
-{% for group in groups.keys() | reject('all') | reject('ungrouped') %}
+{% for group in groups.keys() | difference(['all', 'ungrouped']) %}
   - job_name: {{ group }}
     static_configs:
 {% for host in groups[group] %}