diff --git a/config/puma-config.rb b/config/puma-config.rb
index 45527340..1c15535d 100644
--- a/config/puma-config.rb
+++ b/config/puma-config.rb
@@ -2,7 +2,8 @@ root = File.expand_path('../..', __FILE__)
 
 rackup "#{root}/config.ru"
 
-bind "unix://#{ENV["tmp_dir"]}/nginx.socket"
+tmp_dir = ENV.fetch("tmp_dir", "/tmp")
+bind "unix://#{tmp_dir}/nginx.socket"
 environment ENV['RACK_ENV'] || 'development'
 
 threads 0, 16
diff --git a/config/unicorn.rb b/config/unicorn.rb
index f71a3546..463a017c 100644
--- a/config/unicorn.rb
+++ b/config/unicorn.rb
@@ -3,7 +3,8 @@
 worker_processes Integer(ENV.fetch('WEB_CONCURRENCY')) # amount of unicorn workers to spin up
 timeout 30 # restarts workers that hang for 30 seconds
 
-listen File.expand_path("nginx.socket", ENV["tmp_dir"]), backlog: 1024
+tmp_dir = ENV.fetch("tmp_dir", "/tmp")
+listen File.expand_path("nginx.socket", tmp_dir), backlog: 1024
 
 require 'fileutils'
 before_fork do |server, worker|
@@ -11,5 +12,5 @@ before_fork do |server, worker|
   require 'travis/api/app'
 
   # signal to nginx we're ready
-  FileUtils.touch("#{ENV["tmp_dir"]}/app-initialized")
+  FileUtils.touch("#{tmp_dir}/app-initialized")
 end