diff --git a/50-filter-postfix.conf b/50-filter-postfix.conf
index 98959fc..3b66f50 100644
--- a/50-filter-postfix.conf
+++ b/50-filter-postfix.conf
@@ -207,7 +207,7 @@ filter {
     if [postfix_command_counter_data] {
         grok {
             patterns_dir   => "/etc/logstash/patterns.d"
-            match          => ["postfix_command_counter_data", "^${POSTFIX_COMMAND_COUNTER_DATA}$"]
+            match          => ["postfix_command_counter_data", "^%{POSTFIX_COMMAND_COUNTER_DATA}$"]
             tag_on_failure => ["_grok_postfix_command_counter_data_nomatch"]
             remove_field   => ["postfix_command_counter_data"]
         }