diff --git a/lib/vagrant/util/file_mutex.rb b/lib/vagrant/util/file_mutex.rb
index c005a23a6..2489d1a47 100644
--- a/lib/vagrant/util/file_mutex.rb
+++ b/lib/vagrant/util/file_mutex.rb
@@ -22,7 +22,7 @@ module Vagrant
       end
 
       def unlock
-        File.delete(@mutex_path)
+        File.delete(@mutex_path) if File.file?(@mutex_path)
       end
     end
   end
diff --git a/test/unit/vagrant/action/builtin/box_add_test.rb b/test/unit/vagrant/action/builtin/box_add_test.rb
index 397ff1259..2b53a7f34 100644
--- a/test/unit/vagrant/action/builtin/box_add_test.rb
+++ b/test/unit/vagrant/action/builtin/box_add_test.rb
@@ -102,29 +102,6 @@ describe Vagrant::Action::Builtin::BoxAdd, :skip_windows, :bsdtar do
   end
 
   context "with box file directly" do
-    it "creates and cleans up a lock file" do
-      box_path = iso_env.box2_file(:virtualbox)
-
-      env[:box_name] = "foo"
-      env[:box_url] = box_path.to_s
-
-      
-      expect(box_collection).to receive(:add).with(any_args) { |path, name, version, opts|
-        expect(checksum(path)).to eq(checksum(box_path))
-        expect(name).to eq("foo")
-        expect(version).to eq("0")
-        expect(opts[:metadata_url]).to be_nil
-        true
-      }.and_return(box)
-
-      expect(app).to receive(:call).with(env)
-
-      mutex_path = env[:tmp_path].join("box" + Digest::SHA1.hexdigest("file://" + box_path.to_s) + ".lock").to_s
-      expect(File).to receive(:write).with(mutex_path, "")
-      expect(File).to receive(:delete).with(mutex_path)
-      subject.call(env)
-    end
-
     it "adds it" do
       box_path = iso_env.box2_file(:virtualbox)
 
diff --git a/test/unit/vagrant/util/file_mutex_test.rb b/test/unit/vagrant/util/file_mutex_test.rb
new file mode 100644
index 000000000..0a709f770
--- /dev/null
+++ b/test/unit/vagrant/util/file_mutex_test.rb
@@ -0,0 +1,49 @@
+require File.expand_path("../../../base", __FILE__)
+require 'vagrant/util/file_mutex'
+
+describe Vagrant::Util::FileMutex do
+  include_context "unit"
+
+  let(:temp_dir) { Dir.mktmpdir("vagrant-test-util-mutex_test") }
+
+  after do
+    FileUtils.rm_rf(temp_dir)
+  end
+
+  it "should create a lock file" do
+    mutex_path = temp_dir + "test.lock"
+    instance = described_class.new(mutex_path)
+    instance.lock
+    expect(File).to exist(mutex_path)
+  end
+
+  it "should create and delete lock file" do
+    mutex_path = temp_dir + "test.lock"
+    instance = described_class.new(mutex_path)
+    instance.lock
+    instance.unlock
+    expect(File).to_not exist(mutex_path)
+  end
+
+  it "should not raise an error if the lock file does not exist" do
+    mutex_path = temp_dir + "test.lock"
+    instance = described_class.new(mutex_path)
+    instance.unlock
+    expect(File).to_not exist(mutex_path)
+  end
+
+  it "should run a function with a lock" do
+    mutex_path = temp_dir + "test.lock"
+    instance = described_class.new(mutex_path)
+    instance.with_lock { true }
+    expect(File).to_not exist(mutex_path)
+  end
+
+  it "should fail running a function when locked" do
+    mutex_path = temp_dir + "test.lock"
+    instance = described_class.new(mutex_path)
+    instance.lock
+    expect {instance.with_lock { true }}.
+      to raise_error(Vagrant::Errors::VagrantLocked)
+  end
+end