diff --git a/omnibus/cookbooks/firezone/libraries/config.rb b/omnibus/cookbooks/firezone/libraries/config.rb
index 0654646b1..175103d0f 100644
--- a/omnibus/cookbooks/firezone/libraries/config.rb
+++ b/omnibus/cookbooks/firezone/libraries/config.rb
@@ -175,7 +175,8 @@ class Firezone
     # If the value is a String or Number and the attribute name is attr_name.
     # Used to write out environment variables to a file.
     def self.environment_variables_from(attributes)
-      attributes.reduce '' do |str, attr|
+      acc = ''
+      attributes.reduce acc do |str, attr|
         str << if attr[1].is_a?(String) || attr[1].is_a?(Numeric) || attr[1] == true || attr[1] == false
                  "export #{attr[0].upcase}=\"#{attr[1]}\"\n"
                else