diff --git a/lib/faraday/connection.rb b/lib/faraday/connection.rb
index 76ab8c20..2d93d387 100644
--- a/lib/faraday/connection.rb
+++ b/lib/faraday/connection.rb
@@ -82,6 +82,8 @@ module Faraday
       proxy(options.fetch(:proxy) { ENV['http_proxy'] })
 
       yield self if block_given?
+
+      @headers[:user_agent] ||= "Faraday v#{VERSION}"
     end
 
     # Public: Sets the Hash of URI query unencoded key/value pairs.