diff --git a/lib/mixlib/install.rb b/lib/mixlib/install.rb
index 048cb797..07cea815 100644
--- a/lib/mixlib/install.rb
+++ b/lib/mixlib/install.rb
@@ -18,7 +18,6 @@
 #
 
 require "mixlib/versioning"
-require "mixlib/shellout" unless defined?(Mixlib::ShellOut)
 
 require_relative "install/backend"
 require_relative "install/options"
@@ -252,6 +251,12 @@ def detect_platform
     # Returns a Hash containing the platform info options
     #
     def self.detect_platform
+      # mixlib-shellout (and the etc, fileutils, tmpdir and fcntl trees it
+      # pulls in) is only needed to shell out for platform detection, so it is
+      # loaded here rather than at require time.
+      require "mixlib/shellout" unless defined?(Mixlib::ShellOut)
+      require "tmpdir"
+
       output = if Gem.win_platform?
                  # For Windows we write the detect platform script and execute the
                  # powershell.exe program with Mixlib::ShellOut
diff --git a/spec/functional/mixlib/install/cli_spec.rb b/spec/functional/mixlib/install/cli_spec.rb
index 60acd6de..48e584ec 100644
--- a/spec/functional/mixlib/install/cli_spec.rb
+++ b/spec/functional/mixlib/install/cli_spec.rb
@@ -17,6 +17,7 @@
 
 require "spec_helper"
 require "mixlib/install/cli"
+require "mixlib/shellout"
 require "tmpdir"
 
 describe "mixlib-install executable" do