diff --git a/src/Makefile.am b/src/Makefile.am
index 82a17219..d8885216 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -131,7 +131,8 @@ noinst_LIBRARIES = libnghttpx.a
 libnghttpx_a_SOURCES = ${NGHTTPX_SRCS}
 
 nghttpx_SOURCES = shrpx.cc shrpx.h
-nghttpx_LDADD = libnghttpx.a ${LDADD}
+nghttpx_LDFLAGS =
+nghttpx_LDADD = libnghttpx.a ${LDADD} ${AM_LDFLAGS}
 
 if HAVE_CUNIT
 check_PROGRAMS += nghttpx-unittest
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index 6903dff7..0b18b3eb 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -660,7 +660,7 @@ int HttpDownstreamConnection::on_read() {
     auto nproc = http_parser_execute(&response_htp_, &htp_hooks,
                                      reinterpret_cast<char *>(buf), nread);
 
-    if (nproc != nread) {
+    if (nproc != static_cast<size_t>(nread)) {
       if (LOG_ENABLED(INFO)) {
         DCLOG(INFO, this) << "nproc != nread";
       }
diff --git a/src/shrpx_rate_limit.cc b/src/shrpx_rate_limit.cc
index 259140b6..44867018 100644
--- a/src/shrpx_rate_limit.cc
+++ b/src/shrpx_rate_limit.cc
@@ -24,6 +24,8 @@
  */
 #include "shrpx_rate_limit.h"
 
+#include <limits>
+
 namespace shrpx {
 
 namespace {
@@ -49,7 +51,7 @@ RateLimit::~RateLimit() {
 
 size_t RateLimit::avail() const {
   if (rate_ == 0) {
-    return SSIZE_MAX;
+    return std::numeric_limits<ssize_t>::max();
   }
   return avail_;
 }
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index c7ab5db7..14d971ff 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -706,10 +706,6 @@ ssize_t spdy_data_read_callback(spdylay_session *session, int32_t stream_id,
   auto nread = body->remove(buf, length);
   auto body_empty = body->rleft() == 0;
 
-  if (nread == -1) {
-    ULOG(FATAL, upstream) << "evbuffer_remove() failed";
-    return SPDYLAY_ERR_CALLBACK_FAILURE;
-  }
   if (nread == 0 &&
       downstream->get_response_state() == Downstream::MSG_COMPLETE) {
     if (!downstream->get_upgraded()) {