diff --git a/lib/logstash/outputs/file.rb b/lib/logstash/outputs/file.rb
index 1185601ab..fab057ff8 100644
--- a/lib/logstash/outputs/file.rb
+++ b/lib/logstash/outputs/file.rb
@@ -45,6 +45,9 @@ class LogStash::Outputs::File < LogStash::Outputs::Base
   public
   def register
     require "fileutils" # For mkdir_p
+
+    workers_not_supported
+
     @files = {}
     now = Time.now
     @last_flush_cycle = now
diff --git a/lib/logstash/outputs/zeromq.rb b/lib/logstash/outputs/zeromq.rb
index d529f2bac..92ea5c619 100644
--- a/lib/logstash/outputs/zeromq.rb
+++ b/lib/logstash/outputs/zeromq.rb
@@ -62,7 +62,7 @@ class LogStash::Outputs::ZeroMQ < LogStash::Outputs::Base
     require "logstash/util/zeromq"
     self.class.send(:include, LogStash::Util::ZeroMQ)
 
-    if @mode == "server" && @workers > 1
+    if @mode == "server"
       workers_not_supported("With 'mode => server', only one zeromq socket may bind to a port and may not be shared among threads. Going to single-worker mode for this plugin!")
     end