diff --git a/lib/restclient/request.rb b/lib/restclient/request.rb
index 766831b..6841d2e 100644
--- a/lib/restclient/request.rb
+++ b/lib/restclient/request.rb
@@ -87,7 +87,7 @@ module RestClient
 
     def make_headers user_headers
       unless @cookies.empty?
-        user_headers[:cookie] = @cookies.map { |(key, val)| "#{key.to_s}=#{CGI::unescape(val)}" }.sort.join('; ')
+        user_headers[:cookie] = @cookies.map { |(key, val)| "#{key.to_s}=#{CGI::unescape(val.to_s)}" }.sort.join('; ')
       end
       headers = stringify_headers(default_headers).merge(stringify_headers(user_headers))
       headers.merge!(@payload.headers) if @payload