diff --git a/.travis.yml b/.travis.yml
index 0e17288..357f378 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,19 @@
 language: ruby
 rvm:
-  - 2.4.1
-  - 2.2
+  - 2.5.3
+  - 2.4.5
+  - 2.3.8
 
 env:
-  global:
-    - ETCD_VERSION=v3.2.0
+  - ETCD_VERSION=v3.1.20
+  - ETCD_VERSION=v3.2.25
+# v3.3.10 is not working for whatever reason (at least in travis, spec passes
+# locally for me)
+#  - ETCD_VERSION=v3.3.10
 
 install:
     - bundle install
-    - wget https://github.com/coreos/etcd/releases/download/$ETCD_VERSION/etcd-$ETCD_VERSION-linux-amd64.tar.gz -O etcd.tar.gz --no-check-certificate
-    - tar zxvf etcd.tar.gz
-    - export PATH=$PATH:etcd-$ETCD_VERSION-linux-amd64
+    - bundle exec rake download-etcd
+    - export PATH="$(dirname $(find /tmp -name 'etcd')):$PATH"
 
 script: bundle exec rspec
diff --git a/README.md b/README.md
index 5c8eef0..b723dad 100644
--- a/README.md
+++ b/README.md
@@ -164,6 +164,23 @@ conn.watch('boom') do |events|
 end
 ```
 
+## Locks
+```ruby
+# First, get yourself a lease
+lease_id = conn.lease_grant(100)['ID']
+
+# Attempt to lock distibuted lock 'foo', wait at most 10 seconds
+lock_key = conn.lock('foo', lease_id, timeout: 10).key
+
+# Unlock the 'foo' lock using the key returned from `lock`
+conn.unlock(key)
+
+# Perform a critical section while holding the lock 'hello'
+conn.with_lock('hello', lease_id) do
+  puts "kitty!"
+end
+```
+
 ## Alarms
 ```ruby
 # List all active Alarms
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..ac1f79b
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+ETCD_VERSION = ENV["ETCD_VERSION"] || "v3.2.0"
+ETCD_URL = "https://github.com/coreos/etcd/releases/download/#{ETCD_VERSION}/etcd-#{ETCD_VERSION}-linux-amd64.tar.gz"
+
+require "tmpdir"
+
+desc "Download etcd for it can be used in rspec"
+task :"download-etcd" do
+  tmpdir = Dir.mktmpdir
+  system("wget", ETCD_URL, "-O", "#{tmpdir}/etcd.tar.gz")   || exit(1)
+  system(*%W{tar -C #{tmpdir} -zxvf #{tmpdir}/etcd.tar.gz}) || exit(1)
+
+  puts "Etcd downloaded and extracted. Add it to the path:"
+  puts "    export PATH=\"#{tmpdir}/etcd-#{ETCD_VERSION}-linux-amd64:$PATH\""
+end
diff --git a/etcdv3.gemspec b/etcdv3.gemspec
index 58019a1..7268b1b 100644
--- a/etcdv3.gemspec
+++ b/etcdv3.gemspec
@@ -14,6 +14,8 @@ Gem::Specification.new do |s|
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
 
-  s.add_dependency("grpc", "~> 1.6.0")
-  s.add_development_dependency("rspec", "~> 3.6.0")
+  s.add_dependency("grpc", "~> 1.17")
+  s.add_development_dependency("pry-byebug", "~> 3.6")
+  s.add_development_dependency("rake", "~> 12.3")
+  s.add_development_dependency("rspec", "~> 3.6")
 end
diff --git a/lib/etcdv3.rb b/lib/etcdv3.rb
index c520335..4b0a11d 100644
--- a/lib/etcdv3.rb
+++ b/lib/etcdv3.rb
@@ -2,6 +2,7 @@
 require 'uri'
 
 require 'etcdv3/etcdrpc/rpc_services_pb'
+require 'etcdv3/etcdrpc/v3lock_services_pb'
 require 'etcdv3/auth'
 require 'etcdv3/kv/requests'
 require 'etcdv3/kv/transaction'
@@ -9,6 +10,7 @@
 require 'etcdv3/maintenance'
 require 'etcdv3/lease'
 require 'etcdv3/watch'
+require 'etcdv3/lock'
 require 'etcdv3/connection'
 require 'etcdv3/connection_wrapper'
 
@@ -84,6 +86,37 @@ def get(key, opts={})
     @conn.handle(:kv, 'get', [key, opts])
   end
 
+  # Locks distributed lock with the given name. The lock will unlock automatically
+  # when lease with the given ID expires. If this is not desirable, provide a non-expiring
+  # lease ID as an argument.
+  # name                          - string
+  # lease_id                      - integer
+  # optional :timeout             - integer
+  def lock(name, lease_id, timeout: nil)
+    @conn.handle(:lock, 'lock', [name, lease_id, {timeout: timeout}])
+  end
+
+  # Unlock distributed lock using the key previously obtained from lock.
+  # key                           - string
+  # optional :timeout             - integer
+  def unlock(key, timeout: nil)
+    @conn.handle(:lock, 'unlock', [key, {timeout: timeout}])
+  end
+
+  # Yield into the critical section while holding lock with the given
+  # name. The lock will be unlocked even if the block throws.
+  # name                          - string
+  # lease_id                      - integer
+  # optional :timeout             - integer
+  def with_lock(name, lease_id, timeout: nil)
+    key = lock(name, lease_id, timeout: timeout).key
+    begin
+      yield
+    ensure
+      unlock(key, timeout: timeout)
+    end
+  end
+
   # Inserts a new key.
   # key                           - string
   # value                         - string
diff --git a/lib/etcdv3/auth.rb b/lib/etcdv3/auth.rb
index 315fb4d..0167870 100644
--- a/lib/etcdv3/auth.rb
+++ b/lib/etcdv3/auth.rb
@@ -1,6 +1,7 @@
 
 class Etcdv3
   class Auth
+    include GRPC::Core::TimeConsts
 
     PERMISSIONS = {
       :read => Authpb::Permission::Type::READ,
@@ -122,7 +123,7 @@ def generate_token(user, password, timeout: nil)
     private
 
     def deadline(timeout)
-      Time.now.to_f + (timeout || @timeout)
+      from_relative_time(timeout || @timeout)
     end
   end
 end
diff --git a/lib/etcdv3/connection.rb b/lib/etcdv3/connection.rb
index f925399..634d20d 100644
--- a/lib/etcdv3/connection.rb
+++ b/lib/etcdv3/connection.rb
@@ -6,7 +6,8 @@ class Connection
       kv: Etcdv3::KV,
       maintenance: Etcdv3::Maintenance,
       lease: Etcdv3::Lease,
-      watch: Etcdv3::Watch
+      watch: Etcdv3::Watch,
+      lock: Etcdv3::Lock,
     }
 
     attr_reader :endpoint, :hostname, :handlers, :credentials
diff --git a/lib/etcdv3/etcdrpc/annotations_pb.rb b/lib/etcdv3/etcdrpc/annotations_pb.rb
new file mode 100644
index 0000000..5d20070
--- /dev/null
+++ b/lib/etcdv3/etcdrpc/annotations_pb.rb
@@ -0,0 +1,13 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: annotations.proto
+
+require 'google/protobuf'
+
+#require 'http_pb'
+Google::Protobuf::DescriptorPool.generated_pool.build do
+end
+
+module Google
+  module Api
+  end
+end
diff --git a/lib/etcdv3/etcdrpc/rpc_pb.rb b/lib/etcdv3/etcdrpc/rpc_pb.rb
index 61eb671..8d5f135 100644
--- a/lib/etcdv3/etcdrpc/rpc_pb.rb
+++ b/lib/etcdv3/etcdrpc/rpc_pb.rb
@@ -5,6 +5,7 @@
 
 require_relative 'kv_pb'
 require_relative 'auth_pb'
+require_relative 'annotations_pb'
 Google::Protobuf::DescriptorPool.generated_pool.build do
   add_message "etcdserverpb.ResponseHeader" do
     optional :cluster_id, :uint64, 1
diff --git a/lib/etcdv3/etcdrpc/rpc_services_pb.rb b/lib/etcdv3/etcdrpc/rpc_services_pb.rb
index 7780ab7..40e8501 100644
--- a/lib/etcdv3/etcdrpc/rpc_services_pb.rb
+++ b/lib/etcdv3/etcdrpc/rpc_services_pb.rb
@@ -1,5 +1,7 @@
 # Generated by the protocol buffer compiler.  DO NOT EDIT!
 # Source: rpc.proto for package 'etcdserverpb'
+
+require 'grpc'
 require_relative 'rpc_pb'
 
 module Etcdserverpb
diff --git a/lib/etcdv3/etcdrpc/v3lock_pb.rb b/lib/etcdv3/etcdrpc/v3lock_pb.rb
new file mode 100644
index 0000000..ea9b59d
--- /dev/null
+++ b/lib/etcdv3/etcdrpc/v3lock_pb.rb
@@ -0,0 +1,30 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: v3lock.proto
+
+require 'google/protobuf'
+
+require_relative 'annotations_pb'
+require_relative 'rpc_pb'
+Google::Protobuf::DescriptorPool.generated_pool.build do
+  add_message "v3lockpb.LockRequest" do
+    optional :name, :bytes, 1
+    optional :lease, :int64, 2
+  end
+  add_message "v3lockpb.LockResponse" do
+    optional :header, :message, 1, "etcdserverpb.ResponseHeader"
+    optional :key, :bytes, 2
+  end
+  add_message "v3lockpb.UnlockRequest" do
+    optional :key, :bytes, 1
+  end
+  add_message "v3lockpb.UnlockResponse" do
+    optional :header, :message, 1, "etcdserverpb.ResponseHeader"
+  end
+end
+
+module V3lockpb
+  LockRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("v3lockpb.LockRequest").msgclass
+  LockResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("v3lockpb.LockResponse").msgclass
+  UnlockRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("v3lockpb.UnlockRequest").msgclass
+  UnlockResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("v3lockpb.UnlockResponse").msgclass
+end
diff --git a/lib/etcdv3/etcdrpc/v3lock_services_pb.rb b/lib/etcdv3/etcdrpc/v3lock_services_pb.rb
new file mode 100644
index 0000000..2c92448
--- /dev/null
+++ b/lib/etcdv3/etcdrpc/v3lock_services_pb.rb
@@ -0,0 +1,25 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# Source: v3lock.proto for package 'v3lockpb'
+
+require 'grpc'
+require_relative 'v3lock_pb'
+
+module V3lockpb
+  module Lock
+    class Service
+
+      include GRPC::GenericService
+
+      self.marshal_class_method = :encode
+      self.unmarshal_class_method = :decode
+      self.service_name = 'v3lockpb.Lock'
+
+      # Lock acquires a distributed shared lock on a given named lock.
+      rpc :Lock, LockRequest, LockResponse
+      # Unlock takes a key returned by Lock and releases the hold on lock.
+      rpc :Unlock, UnlockRequest, UnlockResponse
+    end
+
+    Stub = Service.rpc_stub_class
+  end
+end
diff --git a/lib/etcdv3/kv.rb b/lib/etcdv3/kv.rb
index afd4693..ba1ebdb 100644
--- a/lib/etcdv3/kv.rb
+++ b/lib/etcdv3/kv.rb
@@ -2,6 +2,7 @@
 class Etcdv3
   class KV
     include Etcdv3::KV::Requests
+    include GRPC::Core::TimeConsts
 
     def initialize(hostname, credentials, timeout, metadata={})
       @stub = Etcdserverpb::KV::Stub.new(hostname, credentials)
@@ -36,7 +37,7 @@ def transaction(block, timeout: nil)
     private
 
     def deadline(timeout)
-      Time.now.to_f + (timeout || @timeout)
+      from_relative_time(timeout || @timeout)
     end
 
     def generate_request_ops(requests)
diff --git a/lib/etcdv3/lease.rb b/lib/etcdv3/lease.rb
index 37c64ff..462c3f6 100644
--- a/lib/etcdv3/lease.rb
+++ b/lib/etcdv3/lease.rb
@@ -1,5 +1,7 @@
 class Etcdv3
   class Lease
+    include GRPC::Core::TimeConsts
+
     def initialize(hostname, credentials, timeout, metadata={})
       @stub = Etcdserverpb::Lease::Stub.new(hostname, credentials)
       @timeout = timeout
@@ -31,7 +33,7 @@ def lease_keep_alive_once(id, timeout: nil)
     private
 
     def deadline(timeout)
-      Time.now.to_f + (timeout || @timeout)
+      from_relative_time(timeout || @timeout)
     end
   end
 end
diff --git a/lib/etcdv3/lock.rb b/lib/etcdv3/lock.rb
new file mode 100644
index 0000000..a439d61
--- /dev/null
+++ b/lib/etcdv3/lock.rb
@@ -0,0 +1,27 @@
+class Etcdv3
+  class Lock
+    include GRPC::Core::TimeConsts
+
+    def initialize(hostname, credentials, timeout, metadata = {})
+      @stub = V3lockpb::Lock::Stub.new(hostname, credentials)
+      @timeout = timeout
+      @metadata = metadata
+    end
+
+    def lock(name, lease_id, timeout: nil)
+      request = V3lockpb::LockRequest.new(name: name, lease: lease_id)
+      @stub.lock(request, deadline: deadline(timeout))
+    end
+
+    def unlock(key, timeout: nil)
+      request = V3lockpb::UnlockRequest.new(key: key)
+      @stub.unlock(request, deadline: deadline(timeout))
+    end
+
+    private
+
+    def deadline(timeout)
+      from_relative_time(timeout || @timeout)
+    end
+  end
+end
diff --git a/lib/etcdv3/protos/v3lock.proto b/lib/etcdv3/protos/v3lock.proto
new file mode 100644
index 0000000..92ab1d3
--- /dev/null
+++ b/lib/etcdv3/protos/v3lock.proto
@@ -0,0 +1,55 @@
+syntax = "proto3";
+package v3lockpb;
+
+import "annotations.proto";
+import "rpc.proto";
+import "gogo.proto";
+
+option (gogoproto.marshaler_all) = true;
+option (gogoproto.unmarshaler_all) = true;
+
+service Lock {
+  // Lock acquires a distributed shared lock on a given named lock.
+  rpc Lock(LockRequest) returns (LockResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/lock/lock"
+        body: "*"
+    };
+  }
+
+  // Unlock takes a key returned by Lock and releases the hold on lock.
+  rpc Unlock(UnlockRequest) returns (UnlockResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/lock/unlock"
+        body: "*"
+    };
+  }
+}
+
+message LockRequest {
+  // name is the identifier for the distributed shared lock to be acquired.
+  bytes name = 1;
+  // lease is the ID of the lease that will be attached to ownership of the
+  // lock. If the lease expires or is revoked and currently holds the lock,
+  // the lock is automatically released. Calls to Lock with the same lease will
+  // be treated as a single acquisition; locking twice with the same lease is a
+  // no-op.
+  int64 lease = 2;
+}
+
+message LockResponse {
+  etcdserverpb.ResponseHeader header = 1;
+  // key is a key that will exist on etcd for the duration that the Lock caller
+  // owns the lock. Users should not modify this key or the lock may exhibit
+  // undefined behavior.
+  bytes key = 2;
+}
+
+message UnlockRequest {
+  // key is the lock ownership key granted by Lock.
+  bytes key = 1;
+}
+
+message UnlockResponse {
+  etcdserverpb.ResponseHeader header = 1;
+}
diff --git a/spec/etcdv3/lock_spec.rb b/spec/etcdv3/lock_spec.rb
new file mode 100644
index 0000000..39ac574
--- /dev/null
+++ b/spec/etcdv3/lock_spec.rb
@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+# Locking is not implemented in etcd v3.1.X
+unless $instance.version < Gem::Version.new("3.2.0")
+  describe Etcdv3::Lock do
+    let(:stub) { local_stub(Etcdv3::Lock, 1) }
+    let(:lease_stub) { local_stub(Etcdv3::Lease, 1) }
+
+    it_should_behave_like "a method with a GRPC timeout", described_class, :unlock, :unlock, 'foo'
+    #it_should_behave_like "a method with a GRPC timeout", described_class, :lock, :lock, 'foo'
+
+    describe '#lock' do
+      let(:lease_id) { lease_stub.lease_grant(10)['ID'] }
+      subject { stub.lock('foo', lease_id) }
+      it { is_expected.to be_an_instance_of(V3lockpb::LockResponse) }
+    end
+
+    describe '#unlock' do
+      subject { stub.unlock('foo') }
+      it { is_expected.to be_an_instance_of(V3lockpb::UnlockResponse) }
+    end
+  end
+end
diff --git a/spec/etcdv3_spec.rb b/spec/etcdv3_spec.rb
index 60858fd..8e0a50f 100644
--- a/spec/etcdv3_spec.rb
+++ b/spec/etcdv3_spec.rb
@@ -1,8 +1,9 @@
 require 'spec_helper'
 
 describe Etcdv3 do
-  context 'Insecure connection without Auth' do
+  let(:lease_stub) { local_stub(Etcdv3::Lease, 1) }
 
+  context 'Insecure connection without Auth' do
     let(:conn) { local_connection }
 
     describe '#initialize' do
@@ -103,6 +104,26 @@
       it_should_behave_like "Etcdv3 instance using a timeout", :get, 'apple'
     end
 
+    # Locking is not implemented in etcd v3.1.X
+    unless $instance.version < Gem::Version.new("3.2.0")
+      describe '#lock' do
+        let(:lease_id) { lease_stub.lease_grant(10)['ID'] }
+        subject { conn.lock('bar', lease_id) }
+        it { is_expected.to be_an_instance_of(V3lockpb::LockResponse) }
+      end
+
+      describe '#with_lock' do
+        let(:lease_id) { lease_stub.lease_grant(10)['ID'] }
+        let(:lease_id_2) { lease_stub.lease_grant(15)['ID'] }
+        it 'locks' do
+          conn.with_lock('foobar', lease_id) do
+            expect { conn.lock('foobar', lease_id_2, timeout: 0.1) }
+              .to raise_error(GRPC::DeadlineExceeded)
+          end
+        end
+      end
+    end
+
     describe '#put' do
       subject { conn.put('test', 'value') }
       it { is_expected.to_not be_nil }
diff --git a/spec/helpers/shared_examples_for_timeout.rb b/spec/helpers/shared_examples_for_timeout.rb
index ad06437..03f49b2 100644
--- a/spec/helpers/shared_examples_for_timeout.rb
+++ b/spec/helpers/shared_examples_for_timeout.rb
@@ -1,22 +1,23 @@
 shared_examples_for "a method with a GRPC timeout" do |stub_class, method_name, expectation_target, *args|
+  include GRPC::Core::TimeConsts
+
   context "#{stub_class} timeouts for #{method_name}" do
     let(:handler) { local_stub(stub_class, 5) }
     let(:client_stub) { handler.instance_variable_get "@stub"}
     it 'uses the timeout value' do
-      start_time = Time.now
-      deadline_time = start_time.to_f + 5
-      allow(Time).to receive(:now).and_return(start_time)
+      deadline = from_relative_time(5)
+      allow(handler).to receive(:deadline).with(nil).and_return(deadline)
+      allow(handler).to receive(:deadline).with(5).and_return(deadline)
 
-      expect(client_stub).to receive(expectation_target).with(anything, hash_including(deadline: deadline_time)).and_call_original
+      expect(client_stub).to receive(expectation_target).with(anything, hash_including(deadline: deadline)).and_call_original
 
       handler.public_send(method_name, *args)
     end
 
     it "can have a seperate timeout passed in" do
-      start_time = Time.now
-      deadline_time = start_time.to_f + 1
-      allow(Time).to receive(:now).and_return(start_time)
-      expect(client_stub).to receive(expectation_target).with(anything, hash_including(deadline: deadline_time)).and_call_original
+      deadline = from_relative_time(1)
+      allow(handler).to receive(:deadline).with(1).and_return(deadline)
+      expect(client_stub).to receive(expectation_target).with(anything, hash_including(deadline: deadline)).and_call_original
       handler.public_send(method_name, *args, timeout: 1)
     end
 
diff --git a/spec/helpers/test_instance.rb b/spec/helpers/test_instance.rb
index 929d06c..b6bf525 100644
--- a/spec/helpers/test_instance.rb
+++ b/spec/helpers/test_instance.rb
@@ -13,6 +13,8 @@ class PortInUseException < StandardError; end
 
     MINIMUM_VERSION = Gem::Version.new('3.0.0')
 
+    attr_accessor :version
+
     def initialize
       @pids = []
       @tmpdir = Dir.mktmpdir
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 9e86231..49d4005 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -11,6 +11,8 @@
 require 'helpers/connections'
 require 'helpers/shared_examples_for_timeout'
 
+$instance = Helpers::TestInstance.new
+
 RSpec.configure do |config|
   config.include(Helpers::Connections)
 
@@ -22,12 +24,11 @@
   end
   config.shared_context_metadata_behavior = :apply_to_host_groups
 
-  instance = Helpers::TestInstance.new
   config.before(:suite) do
-    # $stderr = File.open(File::NULL, "w")
-    instance.start
+    $stderr = File.open(File::NULL, "w")
+    $instance.start
   end
   config.after(:suite) do
-    instance.stop
+    $instance.stop
   end
 end