diff --git a/angie/conf.dist/core-worker-env.conf.j2 b/angie/conf.dist/core-worker-env.conf.j2
index 3dfd69b..fddbd30 100644
--- a/angie/conf.dist/core-worker-env.conf.j2
+++ b/angie/conf.dist/core-worker-env.conf.j2
@@ -5,23 +5,23 @@
 {%- set c_vars = c_env | dict_keys -%}
 {%- set c_vars_preserve = c_env | dict_empty_keys -%}
 {%- set c_vars_override = c_env | dict_non_empty_keys -%}
-{%- set vars_preserve = ( c_vars_preserve + ( s_vars | list_diff(c_vars) )) | sort -%}
-{#- main part -#}
-{%- if vars_preserve %}
-## preserve
-  {%- for k in vars_preserve %}
-env {{ k }};
-  {%- endfor %}
-{% endif %}
+{%- set vars_preserve = ( c_vars_preserve + s_vars ) | uniq | sort -%}
 
-{%- if c_vars_override %}
+{#- main part -#}
+## preserve
+{%- for k in vars_preserve %}
+env {{ k }};
+{%- endfor %}
+
+{% if c_vars_override %}
 ## WARNING!
 ## explicit environment variables are NOT implemented
 ## reason: envs are supported only for http_perl but not for http_js/stream_js
 ## solution: provide environment variables explicitly
 ##   and then list them in "core_worker_env" key in config
+##
   {%- for k in c_vars_override %}
-    {%- set v = c_env[k] -%}
-# env {{ k }}={{ v.__repr__() }};
+    {#- {%- set v = c_env[k] %} #}
+## env {{ k }}={{ c_env[k].__repr__() }};
   {%- endfor %}
-{% endif %}
+{%- endif %}