diff --git a/lib/language_pack/metadata.rb b/lib/language_pack/metadata.rb
index f6979883c..ea4e91a55 100644
--- a/lib/language_pack/metadata.rb
+++ b/lib/language_pack/metadata.rb
@@ -13,7 +13,7 @@ def initialize(cache)
 
   def read(key)
     full_key = "#{FOLDER}/#{key}"
-    File.read(full_key) if exists?(key)
+    File.read(full_key).chomp if exists?(key)
   end
 
   def exists?(key)
diff --git a/lib/language_pack/ruby.rb b/lib/language_pack/ruby.rb
index 43d5c9799..42e323e48 100644
--- a/lib/language_pack/ruby.rb
+++ b/lib/language_pack/ruby.rb
@@ -115,6 +115,27 @@ def compile
 
 private
 
+  def default_malloc_arena_max?
+    return true if stack_not_14_not_16?
+    return true if "true" == @metadata.read("default_malloc_arena_max")
+
+    if new_app?
+      @metadata.write("default_malloc_arena_max", "true")
+      return true
+    end
+
+    return false
+  end
+
+  def stack_not_14_not_16?
+    case stack
+    when "cedar-14", "heroku-16"
+      return false
+    else
+      return true
+    end
+  end
+
   def warn_bundler_upgrade
     old_bundler_version  = @metadata.read("bundler_version").chomp if @metadata.exists?("bundler_version")
 
@@ -337,6 +358,7 @@ def setup_profiled
       set_env_override "GEM_PATH", "$HOME/#{slug_vendor_base}:$GEM_PATH"
       set_env_override "PATH",      profiled_path.join(":")
 
+      set_env_default "MALLOC_ARENA_MAX", "2"     if default_malloc_arena_max?
       add_to_profiled set_default_web_concurrency if env("SENSIBLE_DEFAULTS")
 
       if ruby_version.jruby?
@@ -518,11 +540,7 @@ def load_default_cache
   # install libyaml into the LP to be referenced for psych compilation
   # @param [String] tmpdir to store the libyaml files
   def install_libyaml(dir)
-    case stack
-    when "cedar-14", "heroku-16"
-    else
-      return
-    end
+    return false if stack_not_14_not_16?
 
     instrument 'ruby.install_libyaml' do
       FileUtils.mkdir_p dir
diff --git a/spec/hatchet/ruby_spec.rb b/spec/hatchet/ruby_spec.rb
index 23fac7fd4..c9d7e2dc8 100644
--- a/spec/hatchet/ruby_spec.rb
+++ b/spec/hatchet/ruby_spec.rb
@@ -27,8 +27,8 @@
 
   describe "2.5.0" do
     it "works" do
-      Hatchet::Runner.new("ruby_25").deploy do
-        # works
+      Hatchet::Runner.new("ruby_25").deploy do |app|
+        #
       end
     end
   end
diff --git a/spec/hatchet/upgrade_ruby_spec.rb b/spec/hatchet/upgrade_ruby_spec.rb
index c3c117f02..a5d1d48c9 100644
--- a/spec/hatchet/upgrade_ruby_spec.rb
+++ b/spec/hatchet/upgrade_ruby_spec.rb
@@ -1,10 +1,12 @@
 require 'spec_helper'
 
 describe "Upgrading ruby apps" do
-  it "upgrades from 2.0.0 to 2.1.0", stack: :cedar do
-    app = Hatchet::Runner.new("default_ruby")
+  it "upgrades from 2.0.0 to 2.1.0" do
+    app = Hatchet::Runner.new("default_ruby", stack: "heroku-16")
     app.setup!
     app.deploy do |app|
+      # MALLOC_ARENA_MAX is persisted
+      expect(app.run('echo "MALLOC_ARENA_MAX_is=$MALLOC_ARENA_MAX"')).to match("MALLOC_ARENA_MAX_is=2")
 
       `echo "" > Gemfile; echo "" > Gemfile.lock`
       puts `env BUNDLE_GEMFILE=./Gemfile bundle install`.inspect
@@ -14,6 +16,9 @@
       expect(app.output).to match("2.4.1")
       expect(app.run("ruby -v")).to match("2.4.1")
       expect(app.output).to match("Ruby version change detected")
+
+      # MALLOC_ARENA_MAX is persisted
+      expect(app.run('echo "MALLOC_ARENA_MAX_is=$MALLOC_ARENA_MAX"')).to match("MALLOC_ARENA_MAX_is=2")
     end
   end
 end