diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index cc92dfb6..f40d2775 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -471,6 +471,8 @@ int Http2Handler::write_clear() {
 int Http2Handler::tls_handshake() {
   ev_io_stop(sessions_->get_loop(), &wev_);
 
+  ERR_clear_error();
+
   auto rv = SSL_do_handshake(ssl_);
 
   if (rv == 0) {
@@ -511,6 +513,8 @@ int Http2Handler::tls_handshake() {
 int Http2Handler::read_tls() {
   uint8_t buf[8192];
 
+  ERR_clear_error();
+
   for (;;) {
     auto rv = SSL_read(ssl_, buf, sizeof(buf));
 
@@ -524,8 +528,8 @@ int Http2Handler::read_tls() {
       case SSL_ERROR_WANT_READ:
         goto fin;
       case SSL_ERROR_WANT_WRITE:
-        ev_io_start(sessions_->get_loop(), &wev_);
-        goto fin;
+        // renegotiation started
+        return -1;
       default:
         return -1;
       }
@@ -546,6 +550,9 @@ fin:
 
 int Http2Handler::write_tls() {
   auto loop = sessions_->get_loop();
+
+  ERR_clear_error();
+
   for (;;) {
     if (wb_.rleft() > 0) {
       const void *p;
@@ -562,8 +569,8 @@ int Http2Handler::write_tls() {
         auto err = SSL_get_error(ssl_, rv);
         switch (err) {
         case SSL_ERROR_WANT_READ:
-          ev_io_stop(loop, &wev_);
-          return 0;
+          // renegotiation started
+          return -1;
         case SSL_ERROR_WANT_WRITE:
           ev_io_start(sessions_->get_loop(), &wev_);
           return 0;
diff --git a/src/h2load.cc b/src/h2load.cc
index 66fd854c..143f96a8 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -567,6 +567,8 @@ int Client::connected() {
 }
 
 int Client::tls_handshake() {
+  ERR_clear_error();
+
   auto rv = SSL_do_handshake(ssl);
 
   if (rv == 0) {
@@ -601,6 +603,9 @@ int Client::tls_handshake() {
 
 int Client::read_tls() {
   uint8_t buf[8192];
+
+  ERR_clear_error();
+
   for (;;) {
     auto rv = SSL_read(ssl, buf, sizeof(buf));
 
@@ -614,8 +619,8 @@ int Client::read_tls() {
       case SSL_ERROR_WANT_READ:
         return 0;
       case SSL_ERROR_WANT_WRITE:
-        ev_io_start(worker->loop, &wev);
-        return 0;
+        // renegotiation started
+        return -1;
       default:
         return -1;
       }
@@ -628,6 +633,8 @@ int Client::read_tls() {
 }
 
 int Client::write_tls() {
+  ERR_clear_error();
+
   for (;;) {
     if (wb.rleft() > 0) {
       const void *p;
@@ -644,8 +651,8 @@ int Client::write_tls() {
         auto err = SSL_get_error(ssl, rv);
         switch (err) {
         case SSL_ERROR_WANT_READ:
-          ev_io_stop(worker->loop, &wev);
-          return 0;
+          // renegotiation started
+          return -1;
         case SSL_ERROR_WANT_WRITE:
           ev_io_start(worker->loop, &wev);
           return 0;
diff --git a/src/nghttp.cc b/src/nghttp.cc
index d55a27ca..5d2481ed 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -1123,6 +1123,8 @@ struct HttpClient {
   int tls_handshake() {
     ev_timer_again(loop, &rt);
 
+    ERR_clear_error();
+
     auto rv = SSL_do_handshake(ssl);
 
     if (rv == 0) {
@@ -1161,6 +1163,8 @@ struct HttpClient {
   int read_tls() {
     ev_timer_again(loop, &rt);
 
+    ERR_clear_error();
+
     uint8_t buf[8192];
     for (;;) {
       auto rv = SSL_read(ssl, buf, sizeof(buf));
@@ -1175,9 +1179,8 @@ struct HttpClient {
         case SSL_ERROR_WANT_READ:
           return 0;
         case SSL_ERROR_WANT_WRITE:
-          ev_io_start(loop, &wev);
-          ev_timer_again(loop, &wt);
-          return 0;
+          // renegotiation started
+          return -1;
         default:
           return -1;
         }
@@ -1192,6 +1195,8 @@ struct HttpClient {
   int write_tls() {
     ev_timer_again(loop, &rt);
 
+    ERR_clear_error();
+
     for (;;) {
       if (wb.rleft() > 0) {
         const void *p;
@@ -1208,9 +1213,8 @@ struct HttpClient {
           auto err = SSL_get_error(ssl, rv);
           switch (err) {
           case SSL_ERROR_WANT_READ:
-            ev_io_stop(loop, &wev);
-            ev_timer_stop(loop, &wt);
-            return 0;
+            // renegotiation started
+            return -1;
           case SSL_ERROR_WANT_WRITE:
             ev_io_start(loop, &wev);
             ev_timer_again(loop, &wt);