diff --git a/templates/mako.j2 b/templates/mako.j2
index 43059ba..7eaf517 100644
--- a/templates/mako.j2
+++ b/templates/mako.j2
@@ -9,7 +9,8 @@
 
 {% for rule in mako_rules %}
 [ {%- for criteria in rule['criterias'] %}
-{{ criteria.field ~ '="' ~ criteria.value ~ '"' }}
+{{ criteria.field }} 
+{%- if criteria.value is defined %}{{ '="' ~ criteria.value ~ '"' }}{% endif %}
 {%- if not loop.last %}{{ ' ' }}{% endif %}
 {%- endfor %}]
 {% for option, value in rule['options'].items() %}