diff --git a/src/shrpx.cc b/src/shrpx.cc
index c2f8f658..7a839f85 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -195,8 +195,8 @@ evconnlistener* create_evlistener(ListenHandler *handler, int family)
         return new_evlistener(handler, fd);
       }
 
-      LOG(WARNING) << "Port was changed between old binary (" << port
-                   << ") and new binary (" << get_config()->port << ")";
+      LOG(WARN) << "Port was changed between old binary (" << port
+                << ") and new binary (" << get_config()->port << ")";
       close(fd);
     }
   }
@@ -255,8 +255,8 @@ evconnlistener* create_evlistener(ListenHandler *handler, int family)
   }
 
   if(!rp) {
-    LOG(WARNING) << "Listening " << (family == AF_INET ? "IPv4" : "IPv6")
-                 << " socket failed";
+    LOG(WARN) << "Listening " << (family == AF_INET ? "IPv4" : "IPv6")
+              << " socket failed";
 
     freeaddrinfo(res);
 
@@ -270,7 +270,7 @@ evconnlistener* create_evlistener(ListenHandler *handler, int family)
   freeaddrinfo(res);
 
   if(rv != 0) {
-    LOG(WARNING) << gai_strerror(rv);
+    LOG(WARN) << gai_strerror(rv);
 
     close(fd);
 
@@ -321,10 +321,10 @@ void save_pid()
     if(chown(get_config()->pid_file.get(),
              get_config()->uid, get_config()->gid)  == -1) {
       auto error = errno;
-      LOG(WARNING) << "Changing owner of pid file "
-                   << get_config()->pid_file.get()
-                   << " failed: "
-                   << strerror(error);
+      LOG(WARN) << "Changing owner of pid file "
+                << get_config()->pid_file.get()
+                << " failed: "
+                << strerror(error);
     }
   }
 }
@@ -1338,7 +1338,7 @@ int main(int argc, char **argv)
       break;
     case 'n':
 #ifdef NOTHREADS
-      LOG(WARNING) << "Threading disabled at build time, no threads created.";
+      LOG(WARN) << "Threading disabled at build time, no threads created.";
 #else
       cmdcfgs.emplace_back(SHRPX_OPT_WORKERS, optarg);
 #endif // NOTHREADS
@@ -1664,15 +1664,15 @@ int main(int argc, char **argv)
        fchown(worker_config->accesslog_fd,
               get_config()->uid, get_config()->gid)  == -1) {
       auto error = errno;
-      LOG(WARNING) << "Changing owner of access log file failed: "
-                   << strerror(error);
+      LOG(WARN) << "Changing owner of access log file failed: "
+                << strerror(error);
     }
     if(worker_config->errorlog_fd != -1 &&
        fchown(worker_config->errorlog_fd,
               get_config()->uid, get_config()->gid) == -1) {
       auto error = errno;
-      LOG(WARNING) << "Changing owner of error log file failed: "
-                   << strerror(error);
+      LOG(WARN) << "Changing owner of error log file failed: "
+                << strerror(error);
     }
   }
 
@@ -1691,10 +1691,10 @@ int main(int argc, char **argv)
     if(get_config()->uid != 0) {
       if(chown(path, get_config()->uid, get_config()->gid) == -1) {
         auto error = errno;
-        LOG(WARNING) << "Changing owner of http2 upstream request header file "
-                     << path
-                     << " failed: "
-                     << strerror(error);
+        LOG(WARN) << "Changing owner of http2 upstream request header file "
+                  << path
+                  << " failed: "
+                  << strerror(error);
       }
     }
   }
@@ -1714,11 +1714,11 @@ int main(int argc, char **argv)
     if(get_config()->uid != 0) {
       if(chown(path, get_config()->uid, get_config()->gid) == -1) {
         auto error = errno;
-        LOG(WARNING) << "Changing owner of http2 upstream response header file"
-                     << " "
-                     << path
-                     << " failed: "
-                     << strerror(error);
+        LOG(WARN) << "Changing owner of http2 upstream response header file"
+                  << " "
+                  << path
+                  << " failed: "
+                  << strerror(error);
       }
     }
   }
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 59577e10..547f968c 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -943,7 +943,7 @@ int parse_config(const char *opt, const char *optarg)
   }
 
   if(util::strieq(opt, "conf")) {
-    LOG(WARNING) << "conf: ignored";
+    LOG(WARN) << "conf: ignored";
 
     return 0;
   }
diff --git a/src/shrpx_connect_blocker.cc b/src/shrpx_connect_blocker.cc
index a40dc412..3954dae7 100644
--- a/src/shrpx_connect_blocker.cc
+++ b/src/shrpx_connect_blocker.cc
@@ -78,7 +78,7 @@ void ConnectBlocker::on_failure()
 
   sleep_ = std::min(128, sleep_ * 2);
 
-  LOG(WARNING) << "connect failure, start sleeping " << sleep_;
+  LOG(WARN) << "connect failure, start sleeping " << sleep_;
 
   timeval t = {sleep_, 0};
 
diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index f781ee82..973bb787 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -975,7 +975,7 @@ event* init_timer(event_base *evbase, event_callback_fn cb, void *arg)
   auto timerev = evtimer_new(evbase, cb, arg);
 
   if(timerev == nullptr) {
-    LOG(WARNING) << "timer initialization failed";
+    LOG(WARN) << "timer initialization failed";
     return nullptr;
   }
 
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index c2e54656..c6629122 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -97,7 +97,7 @@ int Http2Session::disconnect()
       if(fd_ == -1) {
         fd_ = fd;
       } else if(fd != fd_) {
-        SSLOG(WARNING, this) << "fd in bev_ != fd_";
+        SSLOG(WARN, this) << "fd in bev_ != fd_";
         shutdown(fd, SHUT_WR);
         close(fd);
       }
@@ -282,7 +282,7 @@ void eventcb(bufferevent *bev, short events, void *ptr)
     if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
                   reinterpret_cast<char*>(&val), sizeof(val)) == -1) {
       auto error = errno;
-      SSLOG(WARNING, http2session)
+      SSLOG(WARN, http2session)
         << "Setting option TCP_NODELAY failed: errno=" << error;
     }
     return;
@@ -575,7 +575,7 @@ int htp_hdrs_completecb(http_parser *htp)
     return 0;
   }
 
-  SSLOG(WARNING, http2session) << "Tunneling failed";
+  SSLOG(WARN, http2session) << "Tunneling failed";
   http2session->set_state(Http2Session::PROXY_FAILED);
 
   return 0;
@@ -1314,10 +1314,10 @@ int on_frame_not_send_callback(nghttp2_session *session,
                                int lib_error_code, void *user_data)
 {
   auto http2session = static_cast<Http2Session*>(user_data);
-  SSLOG(WARNING, http2session) << "Failed to send control frame type="
-                               << static_cast<uint32_t>(frame->hd.type)
-                               << "lib_error_code=" << lib_error_code << ":"
-                               << nghttp2_strerror(lib_error_code);
+  SSLOG(WARN, http2session) << "Failed to send control frame type="
+                            << static_cast<uint32_t>(frame->hd.type)
+                            << "lib_error_code=" << lib_error_code << ":"
+                            << nghttp2_strerror(lib_error_code);
   if(frame->hd.type == NGHTTP2_HEADERS &&
      frame->headers.cat == NGHTTP2_HCAT_REQUEST) {
     // To avoid stream hanging around, flag Downstream::MSG_RESET and
@@ -1649,8 +1649,8 @@ int Http2Session::consume(int32_t stream_id, size_t len)
   rv = nghttp2_session_consume(session_, stream_id, len);
 
   if(rv != 0) {
-    SSLOG(WARNING, this) << "nghttp2_session_consume() returned error: "
-                         << nghttp2_strerror(rv);
+    SSLOG(WARN, this) << "nghttp2_session_consume() returned error: "
+                      << nghttp2_strerror(rv);
 
     return -1;
   }
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index dd6a1e27..bb159717 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -125,8 +125,8 @@ int Http2Upstream::upgrade_upstream(HttpsUpstream *http)
      settings_payload.size(),
      nullptr);
   if(rv != 0) {
-    ULOG(WARNING, this) << "nghttp2_session_upgrade() returned error: "
-                        << nghttp2_strerror(rv);
+    ULOG(WARN, this) << "nghttp2_session_upgrade() returned error: "
+                     << nghttp2_strerror(rv);
     return -1;
   }
   pre_upstream_.reset(http);
@@ -603,10 +603,10 @@ int on_frame_not_send_callback(nghttp2_session *session,
                                int lib_error_code, void *user_data)
 {
   auto upstream = static_cast<Http2Upstream*>(user_data);
-  ULOG(WARNING, upstream) << "Failed to send control frame type="
-                          << static_cast<uint32_t>(frame->hd.type)
-                          << ", lib_error_code=" << lib_error_code << ":"
-                          << nghttp2_strerror(lib_error_code);
+  ULOG(WARN, upstream) << "Failed to send control frame type="
+                       << static_cast<uint32_t>(frame->hd.type)
+                       << ", lib_error_code=" << lib_error_code << ":"
+                       << nghttp2_strerror(lib_error_code);
   if(frame->hd.type == NGHTTP2_HEADERS &&
      frame->headers.cat == NGHTTP2_HCAT_RESPONSE) {
     // To avoid stream hanging around, issue RST_STREAM.
@@ -924,8 +924,8 @@ void downstream_eventcb(bufferevent *bev, short events, void *ptr)
     int val = 1;
     if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
                   reinterpret_cast<char*>(&val), sizeof(val)) == -1) {
-      DCLOG(WARNING, dconn) << "Setting option TCP_NODELAY failed: errno="
-                            << errno;
+      DCLOG(WARN, dconn) << "Setting option TCP_NODELAY failed: errno="
+                         << errno;
     }
 
     return;
@@ -1425,8 +1425,8 @@ int Http2Upstream::consume(int32_t stream_id, size_t len)
   rv = nghttp2_session_consume(session_, stream_id, len);
 
   if(rv != 0) {
-    ULOG(WARNING, this) << "nghttp2_session_consume() returned error: "
-                        << nghttp2_strerror(rv);
+    ULOG(WARN, this) << "nghttp2_session_consume() returned error: "
+                     << nghttp2_strerror(rv);
     return -1;
   }
 
diff --git a/src/shrpx_log.cc b/src/shrpx_log.cc
index c9c51e6a..f6062a34 100644
--- a/src/shrpx_log.cc
+++ b/src/shrpx_log.cc
@@ -84,7 +84,7 @@ int severity_to_syslog_level(int severity)
     return LOG_INFO;
   case(NOTICE):
     return LOG_NOTICE;
-  case(WARNING):
+  case(WARN):
     return LOG_WARNING;
   case(ERROR):
     return LOG_ERR;
diff --git a/src/shrpx_log.h b/src/shrpx_log.h
index baf56fe2..1166d3b0 100644
--- a/src/shrpx_log.h
+++ b/src/shrpx_log.h
@@ -71,7 +71,7 @@ class Downstream;
   (Log(SEVERITY, __FILE__, __LINE__) << "[DHTTP2:" << HTTP2 << "] ")
 
 enum SeverityLevel {
-  INFO, NOTICE, WARNING, ERROR, FATAL
+  INFO, NOTICE, WARN, ERROR, FATAL
 };
 
 class Log {
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 06c76eca..9fdefc08 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -384,9 +384,9 @@ void on_ctrl_not_send_callback(spdylay_session *session,
                                int error_code, void *user_data)
 {
   auto upstream = static_cast<SpdyUpstream*>(user_data);
-  ULOG(WARNING, upstream) << "Failed to send control frame type=" << type
-                          << ", error_code=" << error_code << ":"
-                          << spdylay_strerror(error_code);
+  ULOG(WARN, upstream) << "Failed to send control frame type=" << type
+                       << ", error_code=" << error_code << ":"
+                       << spdylay_strerror(error_code);
   if(type == SPDYLAY_SYN_REPLY) {
     // To avoid stream hanging around, issue RST_STREAM.
     auto stream_id = frame->syn_reply.stream_id;
@@ -658,8 +658,8 @@ void spdy_downstream_eventcb(bufferevent *bev, short events, void *ptr)
     int val = 1;
     if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
                   reinterpret_cast<char *>(&val), sizeof(val)) == -1) {
-      DCLOG(WARNING, dconn) << "Setting option TCP_NODELAY failed: errno="
-                            << errno;
+      DCLOG(WARN, dconn) << "Setting option TCP_NODELAY failed: errno="
+                         << errno;
     }
     return;
   }
@@ -1134,8 +1134,8 @@ int SpdyUpstream::consume(int32_t stream_id, size_t len)
   rv = spdylay_session_consume(session_, stream_id, len);
 
   if(rv != 0) {
-    ULOG(WARNING, this) << "spdylay_session_consume() returned error: "
-                        << spdylay_strerror(rv);
+    ULOG(WARN, this) << "spdylay_session_consume() returned error: "
+                     << spdylay_strerror(rv);
     return -1;
   }
 
diff --git a/src/shrpx_ssl.cc b/src/shrpx_ssl.cc
index a29152fd..ba0e018f 100644
--- a/src/shrpx_ssl.cc
+++ b/src/shrpx_ssl.cc
@@ -405,8 +405,8 @@ SSL_CTX* create_ssl_client_context()
   SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
 
   if(SSL_CTX_set_default_verify_paths(ssl_ctx) != 1) {
-    LOG(WARNING) << "Could not load system trusted ca certificates: "
-                 << ERR_error_string(ERR_get_error(), nullptr);
+    LOG(WARN) << "Could not load system trusted ca certificates: "
+              << ERR_error_string(ERR_get_error(), nullptr);
   }
 
   if(get_config()->cacert) {
@@ -481,8 +481,7 @@ ClientHandler* accept_connection
   rv = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
                   reinterpret_cast<char *>(&val), sizeof(val));
   if(rv == -1) {
-    LOG(WARNING) << "Setting option TCP_NODELAY failed: errno="
-                 << errno;
+    LOG(WARN) << "Setting option TCP_NODELAY failed: errno=" << errno;
   }
   SSL *ssl = nullptr;
   bufferevent *bev;
@@ -634,7 +633,7 @@ void get_altnames(X509 *cert,
   }
   X509_NAME *subjectname = X509_get_subject_name(cert);
   if(!subjectname) {
-    LOG(WARNING) << "Could not get X509 name object from the certificate.";
+    LOG(WARN) << "Could not get X509 name object from the certificate.";
     return;
   }
   int lastpos = -1;