diff --git a/lib/pitchfork/flock.rb b/lib/pitchfork/flock.rb
index ad38cb71..4d76d3f6 100644
--- a/lib/pitchfork/flock.rb
+++ b/lib/pitchfork/flock.rb
@@ -19,6 +19,10 @@ def at_fork
       nil
     end
 
+    def to_io
+      @file
+    end
+
     def unlink
       File.unlink(@file.path)
     rescue Errno::ENOENT
diff --git a/lib/pitchfork/http_server.rb b/lib/pitchfork/http_server.rb
index e4067742..f524e563 100644
--- a/lib/pitchfork/http_server.rb
+++ b/lib/pitchfork/http_server.rb
@@ -129,6 +129,7 @@ def initialize(app, options = {})
       @respawn = false
       @last_check = Pitchfork.time_now
       @promotion_lock = Flock.new("pitchfork-promotion")
+      Info.keep_io(@promotion_lock)
 
       options = options.dup
       @ready_pipe = options.delete(:ready_pipe)
@@ -180,6 +181,7 @@ def start(sync = true)
       # It's also used by newly spawned children to send their soft_signal pipe
       # to the master when they are spawned.
       @control_socket.replace(Pitchfork.socketpair)
+      Info.keep_ios(@control_socket)
       @master_pid = $$
 
       # setup signal handlers before writing pid file in case people get
@@ -264,6 +266,7 @@ def listen(address, opt = {}.merge(listener_opts[address] || {}))
           io = server_cast(io)
         end
         logger.info "listening on addr=#{sock_name(io)} fd=#{io.fileno}"
+        Info.keep_io(io)
         LISTENERS << io
         io
       rescue Errno::EADDRINUSE => err
diff --git a/lib/pitchfork/info.rb b/lib/pitchfork/info.rb
index f6562b5e..85f20cf8 100644
--- a/lib/pitchfork/info.rb
+++ b/lib/pitchfork/info.rb
@@ -6,10 +6,40 @@ module Pitchfork
   module Info
     @workers_count = 0
     @fork_safe = true
+    @kept_ios = ObjectSpace::WeakMap.new
 
     class << self
       attr_accessor :workers_count
 
+      def keep_io(io)
+        @kept_ios[io] = io if io && !io.to_io.closed?
+        io
+      end
+
+      def keep_ios(ios)
+        ios.each { |io| keep_io(io) }
+      end
+
+      def close_all_fds!
+        ignored_fds = [$stdin.to_i, $stdout.to_i, $stderr.to_i]
+        @kept_ios.each_value do |io_like|
+          if io = io_like&.to_io
+            ignored_fds << io.to_i unless io.closed?
+          end
+        end
+
+        all_fds = Dir.children("/dev/fd").map(&:to_i)
+        all_fds -= ignored_fds
+
+        all_fds.each do |fd|
+          IO.for_fd(fd).close
+        rescue ArgumentError
+          # RubyVM internal file descriptor, leave it alone
+        rescue Errno::EBADF
+          # Likely a race condition
+        end
+      end
+
       def fork_safe?
         @fork_safe
       end
diff --git a/lib/pitchfork/worker.rb b/lib/pitchfork/worker.rb
index aa323209..d2b1d341 100644
--- a/lib/pitchfork/worker.rb
+++ b/lib/pitchfork/worker.rb
@@ -198,7 +198,7 @@ def close # :nodoc:
     end
 
     def create_socketpair!
-      @to_io, @master = Pitchfork.socketpair
+      @to_io, @master = Info.keep_ios(Pitchfork.socketpair)
     end
 
     def after_fork_in_child
@@ -208,6 +208,7 @@ def after_fork_in_child
     private
 
     def pipe=(socket)
+      Info.keep_io(socket)
       @master = MessageSocket.new(socket)
     end
 
diff --git a/test/slow/test_server.rb b/test/slow/test_server.rb
index f5cce38c..cd4faec7 100644
--- a/test/slow/test_server.rb
+++ b/test/slow/test_server.rb
@@ -80,6 +80,7 @@ class WebServerStartTest < Pitchfork::Test
 
   def test_preload_app
     tmp = Tempfile.new('test_preload_app_config')
+    Pitchfork::Info.keep_io(tmp)
     ObjectSpace.undefine_finalizer(tmp)
     app = lambda { ||
       tmp.sysseek(0)
diff --git a/test/slow/test_signals.rb b/test/slow/test_signals.rb
index 745c2cd1..0a82de80 100644
--- a/test/slow/test_signals.rb
+++ b/test/slow/test_signals.rb
@@ -25,8 +25,8 @@ def setup
     @bs = 1 * 1024 * 1024
     @count = 100
     @port = unused_port
-    @sock = Tempfile.new('pitchfork.sock')
-    @tmp = Tempfile.new('pitchfork.write')
+    @sock = Pitchfork::Info.keep_io(Tempfile.new('pitchfork.sock'))
+    @tmp = Pitchfork::Info.keep_io(Tempfile.new('pitchfork.write'))
     @tmp.sync = true
     File.unlink(@sock.path)
     File.unlink(@tmp.path)
@@ -75,7 +75,7 @@ def test_worker_dies_on_dead_master
   end
 
   def test_sleepy_kill
-    rd, wr = IO.pipe
+    rd, wr = Pitchfork::Info.keep_ios(IO.pipe)
     pid = fork {
       rd.close
       app = lambda { |env| wr.syswrite('.'); sleep; [ 200, {}, [] ] }
diff --git a/test/slow/test_upload.rb b/test/slow/test_upload.rb
index 1897066e..87e9b30f 100644
--- a/test/slow/test_upload.rb
+++ b/test/slow/test_upload.rb
@@ -143,7 +143,7 @@ def test_put_keepalive_truncates_small_overwrite
   end
 
   def test_put_excessive_overwrite_closed
-    tmp = Tempfile.new('overwrite_check')
+    tmp = Pitchfork::Info.keep_io(Tempfile.new('overwrite_check'))
     tmp.sync = true
     start_server(lambda { |env|
       nr = 0
diff --git a/test/unit/test_ccc.rb b/test/unit/test_ccc.rb
index 87f71b58..4f707d22 100644
--- a/test/unit/test_ccc.rb
+++ b/test/unit/test_ccc.rb
@@ -6,9 +6,9 @@ def test_ccc_tcpi
     host = '127.0.0.1'
     port = unused_port
 
-    rd, wr = IO.pipe
-    sleep_pipe = IO.pipe
-    ready_read, ready_write = IO.pipe
+    rd, wr = Pitchfork::Info.keep_ios(IO.pipe)
+    sleep_pipe = Pitchfork::Info.keep_ios(IO.pipe)
+    ready_read, ready_write = Pitchfork::Info.keep_ios(IO.pipe)
 
     pid = fork do
       ready_read.close