diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index adad237..badebfc 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-20.04, macos-10.15, macos-11.0]
+        os: [ubuntu-18.04, ubuntu-20.04, macos-10.15, macos-11.0]
         etcd: [v3.2.26, v3.3.11, v3.4.13]
     steps:
       - uses: actions/checkout@v2
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9784e16..b067cbd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -61,8 +61,6 @@ if(NOT CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wno-string-compare -std=c++11")
 endif()
 
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
 
 add_subdirectory(src)
diff --git a/README.md b/README.md
index 6fc79d0..1b621af 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ i.e., `ETCDCTL_API=3`.
 ### Supported OS environments
 
 + **Linux**
-  - Ubuntu 18.04, requires upgrade boost and grpc libraries.
+  - Ubuntu 18.04, requires upgrade grpc libraries (has been tested with 1.27.x).
   - Ubuntu 20.04
 + **MacOS**
   - MacOS 10.15
diff --git a/etcd/KeepAlive.hpp b/etcd/KeepAlive.hpp
index 9a90a5f..1bba3f1 100644
--- a/etcd/KeepAlive.hpp
+++ b/etcd/KeepAlive.hpp
@@ -6,7 +6,12 @@
 #include "etcd/Client.hpp"
 #include "etcd/Response.hpp"
 
+#include <boost/config.hpp>
+#if BOOST_VERSION >= 106600
 #include <boost/asio/io_context.hpp>
+#else
+#include <boost/asio/io_service.hpp>
+#endif
 #include <boost/asio/steady_timer.hpp>
 
 #include <grpc++/grpc++.h>
@@ -55,7 +60,11 @@ namespace etcd
     int ttl;
     int64_t lease_id;
     bool continue_next;
+#if BOOST_VERSION >= 106600
     boost::asio::io_context context;
+#else
+    boost::asio::io_service context;
+#endif
     std::unique_ptr<boost::asio::steady_timer> keepalive_timer_;
   };
 }
diff --git a/src/KeepAlive.cpp b/src/KeepAlive.cpp
index f15701a..3685260 100644
--- a/src/KeepAlive.cpp
+++ b/src/KeepAlive.cpp
@@ -1,3 +1,5 @@
+#include <chrono>
+
 #include "etcd/KeepAlive.hpp"
 #include "etcd/v3/AsyncLeaseAction.hpp"
 
@@ -70,7 +72,7 @@ void etcd::KeepAlive::refresh()
   }
 #endif
   keepalive_timer_.reset(new boost::asio::steady_timer(
-      context, boost::asio::chrono::seconds(keepalive_ttl)));
+      context, std::chrono::seconds(keepalive_ttl)));
   keepalive_timer_->async_wait([this](const boost::system::error_code& error) {
     if (error) {
 #ifndef NDEBUG
diff --git a/tst/WatcherTest.cpp b/tst/WatcherTest.cpp
index 44edcda..625babd 100644
--- a/tst/WatcherTest.cpp
+++ b/tst/WatcherTest.cpp
@@ -32,17 +32,17 @@ TEST_CASE("create watcher with cancel")
 
   watcher_called = 0;
   etcd::Watcher watcher(etcd_uri, "/test", printResponse, true);
-  std::this_thread::sleep_for(std::chrono::seconds(1));
+  std::this_thread::sleep_for(std::chrono::seconds(3));
   etcd.set("/test/key", "42");
   etcd.set("/test/key", "43");
   etcd.rm("/test/key");
   etcd.set("/test/key", "44");
-  std::this_thread::sleep_for(std::chrono::seconds(1));
+  std::this_thread::sleep_for(std::chrono::seconds(3));
   CHECK(4 == watcher_called);
   watcher.Cancel();
   etcd.set("/test/key", "50");
   etcd.set("/test/key", "51");
-  std::this_thread::sleep_for(std::chrono::seconds(1));
+  std::this_thread::sleep_for(std::chrono::seconds(3));
   CHECK(4 == watcher_called);
 
   etcd.rmdir("/test", true);
@@ -57,11 +57,11 @@ TEST_CASE("create watcher")
   watcher_called = 0;
   {
     etcd::Watcher watcher(etcd_uri, "/test", printResponse, true);
-    std::this_thread::sleep_for(std::chrono::seconds(1));
+    std::this_thread::sleep_for(std::chrono::seconds(3));
     etcd.set("/test/key", "42");
     etcd.set("/test/key", "43");
+    std::this_thread::sleep_for(std::chrono::seconds(3));
   }
-  
   CHECK(2 == watcher_called);
   etcd.rmdir("/test", true).error_code();
 }