diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 822ce36a..72bd104a 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -681,9 +681,15 @@ int HttpsUpstream::on_downstream_body(Downstream *downstream,
       return -1;
     }
   }
-  evbuffer_add(output, data, len);
+  if(evbuffer_add(output, data, len) != 0) {
+    ULOG(FATAL, this) << "evbuffer_add() failed";
+    return -1;
+  }
   if(downstream->get_chunked_response()) {
-    evbuffer_add(output, "\r\n", 2);
+    if(evbuffer_add(output, "\r\n", 2) != 0) {
+      ULOG(FATAL, this) << "evbuffer_add() failed";
+      return -1;
+    }
   }
   return 0;
 }
diff --git a/src/shrpx_listen_handler.cc b/src/shrpx_listen_handler.cc
index 3b9aa5a0..4a9cf4ba 100644
--- a/src/shrpx_listen_handler.cc
+++ b/src/shrpx_listen_handler.cc
@@ -109,7 +109,10 @@ int ListenHandler::accept_connection(evutil_socket_t fd,
     memcpy(&wev.client_addr, addr, addrlen);
     wev.client_addrlen = addrlen;
     evbuffer *output = bufferevent_get_output(workers_[idx].bev);
-    evbuffer_add(output, &wev, sizeof(wev));
+    if(evbuffer_add(output, &wev, sizeof(wev)) != 0) {
+      LLOG(FATAL, this) << "evbuffer_add() failed";
+      return -1;
+    }
   }
   return 0;
 }
diff --git a/src/shrpx_spdy_session.cc b/src/shrpx_spdy_session.cc
index f177d860..5a7a27c9 100644
--- a/src/shrpx_spdy_session.cc
+++ b/src/shrpx_spdy_session.cc
@@ -228,8 +228,11 @@ void eventcb(bufferevent *bev, short events, void *ptr)
     }
     int fd = bufferevent_getfd(bev);
     int val = 1;
-    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
-               reinterpret_cast<char *>(&val), sizeof(val));
+    if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
+                  reinterpret_cast<char *>(&val), sizeof(val)) == -1) {
+      SSLOG(WARNING, spdy) << "Setting option TCP_NODELAY failed: "
+                           << strerror(errno);
+    }
   } else if(events & BEV_EVENT_EOF) {
     if(LOG_ENABLED(INFO)) {
       SSLOG(INFO, spdy) << "EOF";
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 85608ef1..dfdff29f 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -508,8 +508,11 @@ void spdy_downstream_eventcb(bufferevent *bev, short events, void *ptr)
     }
     int fd = bufferevent_getfd(bev);
     int val = 1;
-    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
-               reinterpret_cast<char *>(&val), sizeof(val));
+    if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY,
+                  reinterpret_cast<char *>(&val), sizeof(val)) == -1) {
+      DCLOG(WARNING, dconn) << "Setting option TCP_NODELAY failed: "
+                            << strerror(errno);
+    }
   } else if(events & BEV_EVENT_EOF) {
     if(LOG_ENABLED(INFO)) {
       DCLOG(INFO, dconn) << "EOF. stream_id=" << downstream->get_stream_id();
diff --git a/src/shrpx_thread_event_receiver.cc b/src/shrpx_thread_event_receiver.cc
index 3192f6ee..f29a169d 100644
--- a/src/shrpx_thread_event_receiver.cc
+++ b/src/shrpx_thread_event_receiver.cc
@@ -46,7 +46,12 @@ void ThreadEventReceiver::on_read(bufferevent *bev)
   evbuffer *input = bufferevent_get_input(bev);
   while(evbuffer_get_length(input) >= sizeof(WorkerEvent)) {
     WorkerEvent wev;
-    evbuffer_remove(input, &wev, sizeof(WorkerEvent));
+    int nread = evbuffer_remove(input, &wev, sizeof(wev));
+    if(nread != sizeof(wev)) {
+      TLOG(FATAL, this) << "evbuffer_remove() removed fewer bytes. Expected:"
+                        << sizeof(wev) << " Actual:" << nread;
+      continue;
+    }
     if(LOG_ENABLED(INFO)) {
       TLOG(INFO, this) << "WorkerEvent: client_fd=" << wev.client_fd
                        << ", addrlen=" << wev.client_addrlen;