diff --git a/hydra-derivatives.gemspec b/hydra-derivatives.gemspec
index 38d9fc1..bacde4a 100644
--- a/hydra-derivatives.gemspec
+++ b/hydra-derivatives.gemspec
@@ -4,7 +4,7 @@ version = File.read(File.expand_path("../VERSION", __FILE__)).strip
 
 Gem::Specification.new do |spec|
   spec.name          = "hydra-derivatives"
-  spec.version       = version 
+  spec.version       = version
   spec.authors       = ["Justin Coyne"]
   spec.email         = ["justin@curationexperts.com"]
   spec.description   = %q{Derivative generation plugin for hydra}
@@ -25,6 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'active-fedora'
   spec.add_dependency 'hydra-file_characterization'
   spec.add_dependency 'mini_magick'
+  spec.add_dependency 'posix-spawn'
   spec.add_dependency 'activesupport', '>= 3.2.13', '< 5.0'
 end
 
diff --git a/lib/hydra/derivatives/shell_based_processor.rb b/lib/hydra/derivatives/shell_based_processor.rb
index 5ae3482..d4c188b 100644
--- a/lib/hydra/derivatives/shell_based_processor.rb
+++ b/lib/hydra/derivatives/shell_based_processor.rb
@@ -1,16 +1,13 @@
 # An abstract class for asyncronous jobs that transcode files using FFMpeg
 
 require 'tmpdir'
-require 'open3'
+require 'posix-spawn'
 
 module Hydra
   module Derivatives
     module ShellBasedProcessor
       extend ActiveSupport::Concern
 
-      included do
-        extend Open3
-      end
 
       def process
         directives.each do |name, args|
@@ -39,15 +36,17 @@ def encode_datastream(dest_dsid, file_suffix, mime_type, options = '')
 
       module ClassMethods
         def execute(command)
-          stdin, stdout, stderr, wait_thr = popen3(command)
-          stdin.close
-          out = stdout.read
-          stdout.close
-          err = stderr.read
-          stderr.close
-          raise "Unable to execute command \"#{command}\"\n#{err}" unless wait_thr.value.success?
+          stdout, stderr, status = execute_posix_spawn(*command)
+          raise "Unable to execute command \"#{command}\"\n#{stderr}" unless status.exitstatus.success?
         end
       end
+
+    def execute_posix_spawn(*command)
+      pid, stdin, stdout, stderr = POSIX::Spawn.popen4(*command)
+      Process.waitpid(pid)
+
+      [stdout.read, stderr.read, $?]
+    end
     end
   end
 end