diff --git a/lib/puma/const.rb b/lib/puma/const.rb
index f10c27da..7a7ca815 100644
--- a/lib/puma/const.rb
+++ b/lib/puma/const.rb
@@ -1,5 +1,3 @@
-require 'set'
-
 module Puma
 
   # Every standard HTTP code mapped to the appropriate message.  These are
@@ -46,7 +44,9 @@ module Puma
   }
 
   # For some HTTP status codes the client only expects headers.
-  STATUS_WITH_NO_ENTITY_BODY = Set.new((100..199).to_a << 204 << 205 << 304)
+  STATUS_WITH_NO_ENTITY_BODY = {
+    204 => true, 205 => true, 304 => true
+  }
 
   # Frequently used constants when constructing requests or responses.  Many times
   # the constant just refers to a string with the same contents.  Using these constants
diff --git a/lib/puma/server.rb b/lib/puma/server.rb
index e18b3c80..03a6f618 100644
--- a/lib/puma/server.rb
+++ b/lib/puma/server.rb
@@ -341,7 +341,7 @@ module Puma
         end
 
         content_length = nil
-        no_body = STATUS_WITH_NO_ENTITY_BODY.include? status
+        no_body = false
 
         if res_body.kind_of? Array and res_body.size == 1
           content_length = res_body[0].size
@@ -366,6 +366,8 @@ module Puma
             client.write " "
             client.write HTTP_STATUS_CODES[status]
             client.write "\r\n"
+
+            no_body = status < 200 || STATUS_WITH_NO_ENTITY_BODY[status]
           end
         else
           allow_chunked = false
@@ -382,6 +384,8 @@ module Puma
             client.write " "
             client.write HTTP_STATUS_CODES[status]
             client.write "\r\n"
+
+            no_body = status < 200 || STATUS_WITH_NO_ENTITY_BODY[status]
           end
         end