diff --git a/prometheus/files/alertmanager.yml b/prometheus/files/alertmanager.yml
index 3221b44..0e90d5f 100644
--- a/prometheus/files/alertmanager.yml
+++ b/prometheus/files/alertmanager.yml
@@ -155,6 +155,9 @@
       {%- if slack.channel is defined %}
       channel: {{ slack.channel }}
       {%- endif %}
+      {%- if slack.http_config is defined %}
+      {{ http_config_entry(slack.http_config) | indent(6) }}
+      {%- endif %}
     {%- endfor %}
   {%- endif %}
   {%- if config.email_configs is defined %}