diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0648f6f5..46db4865 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -48,7 +48,7 @@ if(ENABLE_APP)
   set(NGHTTP_SOURCES
     ${HELPER_OBJECTS}
     nghttp.cc
-    ssl.cc
+    tls.cc
   )
   if(HAVE_LIBXML2)
     list(APPEND NGHTTP_SOURCES HtmlParser.cc)
@@ -58,7 +58,7 @@ if(ENABLE_APP)
   set(NGHTTPD_SOURCES
     ${HELPER_OBJECTS}
     nghttpd.cc
-    ssl.cc
+    tls.cc
     HttpServer.cc
   )
 
@@ -67,7 +67,7 @@ if(ENABLE_APP)
     util.cc
     http2.cc h2load.cc
     timegm.c
-    ssl.cc
+    tls.cc
     h2load_http2_session.cc
     h2load_http1_session.cc
   )
@@ -82,7 +82,7 @@ if(ENABLE_APP)
   set(NGHTTPX_SRCS
     util.cc http2.cc timegm.c
     app_helper.cc
-    ssl.cc
+    tls.cc
     shrpx_config.cc
     shrpx_accept_handler.cc
     shrpx_connection_handler.cc
@@ -216,7 +216,7 @@ endif()
 if(ENABLE_ASIO_LIB)
   set(NGHTTP2_ASIO_SOURCES
     util.cc http2.cc
-    ssl.cc
+    tls.cc
     timegm.c
     asio_common.cc
     asio_io_service_pool.cc
diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index 7dc16765..deb50d1c 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -60,7 +60,7 @@
 #include "app_helper.h"
 #include "http2.h"
 #include "util.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 
 #ifndef O_BINARY
@@ -877,7 +877,7 @@ int Http2Handler::connection_made() {
     }
   }
 
-  if (ssl_ && !nghttp2::ssl::check_http2_requirement(ssl_)) {
+  if (ssl_ && !nghttp2::tls::check_http2_requirement(ssl_)) {
     terminate_session(NGHTTP2_INADEQUATE_SECURITY);
   }
 
@@ -2122,14 +2122,14 @@ int HttpServer::run() {
     SSL_CTX_set_mode(ssl_ctx, SSL_MODE_AUTO_RETRY);
     SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
 
-    if (nghttp2::ssl::ssl_ctx_set_proto_versions(
-            ssl_ctx, nghttp2::ssl::NGHTTP2_TLS_MIN_VERSION,
-            nghttp2::ssl::NGHTTP2_TLS_MAX_VERSION) != 0) {
+    if (nghttp2::tls::ssl_ctx_set_proto_versions(
+            ssl_ctx, nghttp2::tls::NGHTTP2_TLS_MIN_VERSION,
+            nghttp2::tls::NGHTTP2_TLS_MAX_VERSION) != 0) {
       std::cerr << "Could not set TLS versions" << std::endl;
       return -1;
     }
 
-    if (SSL_CTX_set_cipher_list(ssl_ctx, ssl::DEFAULT_CIPHER_LIST) == 0) {
+    if (SSL_CTX_set_cipher_list(ssl_ctx, tls::DEFAULT_CIPHER_LIST) == 0) {
       std::cerr << ERR_error_string(ERR_get_error(), nullptr) << std::endl;
       return -1;
     }
diff --git a/src/Makefile.am b/src/Makefile.am
index ea3f8a30..297c0b58 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -81,10 +81,10 @@ endif # HAVE_LIBXML2
 
 nghttp_SOURCES = ${HELPER_OBJECTS} ${HELPER_HFILES} nghttp.cc nghttp.h \
 	${HTML_PARSER_OBJECTS} ${HTML_PARSER_HFILES} \
-	ssl.cc ssl.h
+	tls.cc tls.h
 
 nghttpd_SOURCES = ${HELPER_OBJECTS} ${HELPER_HFILES} nghttpd.cc \
-	ssl.cc ssl.h \
+	tls.cc tls.h \
 	HttpServer.cc HttpServer.h
 
 bin_PROGRAMS += h2load
@@ -92,7 +92,7 @@ bin_PROGRAMS += h2load
 h2load_SOURCES = util.cc util.h \
 	http2.cc http2.h h2load.cc h2load.h \
 	timegm.c timegm.h \
-	ssl.cc ssl.h \
+	tls.cc tls.h \
 	h2load_session.h \
 	h2load_http2_session.cc h2load_http2_session.h \
 	h2load_http1_session.cc h2load_http1_session.h
@@ -104,7 +104,7 @@ endif # HAVE_SPDYLAY
 NGHTTPX_SRCS = \
 	util.cc util.h http2.cc http2.h timegm.c timegm.h base64.h \
 	app_helper.cc app_helper.h \
-	ssl.cc ssl.h \
+	tls.cc tls.h \
 	shrpx_config.cc shrpx_config.h \
 	shrpx_error.h \
 	shrpx_accept_handler.cc shrpx_accept_handler.h \
@@ -240,7 +240,7 @@ lib_LTLIBRARIES = libnghttp2_asio.la
 
 libnghttp2_asio_la_SOURCES = \
 	util.cc util.h http2.cc http2.h \
-	ssl.cc ssl.h \
+	tls.cc tls.h \
 	ssl_compat.h \
 	timegm.c timegm.h \
 	asio_common.cc asio_common.h \
diff --git a/src/asio_client_tls_context.cc b/src/asio_client_tls_context.cc
index 75830013..3291885b 100644
--- a/src/asio_client_tls_context.cc
+++ b/src/asio_client_tls_context.cc
@@ -28,7 +28,7 @@
 
 #include <boost/asio/ssl.hpp>
 
-#include "ssl.h"
+#include "tls.h"
 #include "util.h"
 
 namespace nghttp2 {
diff --git a/src/asio_server_http2_impl.cc b/src/asio_server_http2_impl.cc
index da138b7a..83368d45 100644
--- a/src/asio_server_http2_impl.cc
+++ b/src/asio_server_http2_impl.cc
@@ -28,7 +28,7 @@
 
 #include "asio_server.h"
 #include "util.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 
 namespace nghttp2 {
diff --git a/src/asio_server_tls_context.cc b/src/asio_server_tls_context.cc
index 53fc9883..aa73cc50 100644
--- a/src/asio_server_tls_context.cc
+++ b/src/asio_server_tls_context.cc
@@ -28,7 +28,7 @@
 
 #include <boost/asio/ssl.hpp>
 
-#include "ssl.h"
+#include "tls.h"
 #include "util.h"
 
 namespace nghttp2 {
@@ -72,7 +72,7 @@ configure_tls_context_easy(boost::system::error_code &ec,
   SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
   SSL_CTX_set_mode(ctx, SSL_MODE_RELEASE_BUFFERS);
 
-  SSL_CTX_set_cipher_list(ctx, ssl::DEFAULT_CIPHER_LIST);
+  SSL_CTX_set_cipher_list(ctx, tls::DEFAULT_CIPHER_LIST);
 
 #ifndef OPENSSL_NO_EC
   auto ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
diff --git a/src/h2load.cc b/src/h2load.cc
index cbf0e51a..51da4e44 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -59,7 +59,7 @@
 #ifdef HAVE_SPDYLAY
 #include "h2load_spdy_session.h"
 #endif // HAVE_SPDYLAY
-#include "ssl.h"
+#include "tls.h"
 #include "http2.h"
 #include "util.h"
 #include "template.h"
@@ -79,7 +79,7 @@ bool recorded(const std::chrono::steady_clock::time_point &t) {
 } // namespace
 
 Config::Config()
-    : ciphers(ssl::DEFAULT_CIPHER_LIST),
+    : ciphers(tls::DEFAULT_CIPHER_LIST),
       data_length(-1),
       addrs(nullptr),
       nreqs(1),
@@ -625,7 +625,7 @@ void Client::report_tls_info() {
   if (worker->id == 0 && !worker->tls_info_report_done) {
     worker->tls_info_report_done = true;
     auto cipher = SSL_get_current_cipher(ssl);
-    std::cout << "TLS Protocol: " << ssl::get_tls_protocol(ssl) << "\n"
+    std::cout << "TLS Protocol: " << tls::get_tls_protocol(ssl) << "\n"
               << "Cipher: " << SSL_CIPHER_get_name(cipher) << std::endl;
     print_server_tmp_key(ssl);
   }
@@ -1822,10 +1822,10 @@ Options:
 } // namespace
 
 int main(int argc, char **argv) {
-  ssl::libssl_init();
+  tls::libssl_init();
 
 #ifndef NOTHREADS
-  ssl::LibsslGlobalLock lock;
+  tls::LibsslGlobalLock lock;
 #endif // NOTHREADS
 
   std::string datafile;
@@ -2242,9 +2242,9 @@ int main(int argc, char **argv) {
   SSL_CTX_set_mode(ssl_ctx, SSL_MODE_AUTO_RETRY);
   SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
 
-  if (nghttp2::ssl::ssl_ctx_set_proto_versions(
-          ssl_ctx, nghttp2::ssl::NGHTTP2_TLS_MIN_VERSION,
-          nghttp2::ssl::NGHTTP2_TLS_MAX_VERSION) != 0) {
+  if (nghttp2::tls::ssl_ctx_set_proto_versions(
+          ssl_ctx, nghttp2::tls::NGHTTP2_TLS_MIN_VERSION,
+          nghttp2::tls::NGHTTP2_TLS_MAX_VERSION) != 0) {
     std::cerr << "Could not set TLS versions" << std::endl;
     exit(EXIT_FAILURE);
   }
diff --git a/src/nghttp.cc b/src/nghttp.cc
index b94e2ba9..d05e28ee 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -57,7 +57,7 @@
 #include "HtmlParser.h"
 #include "util.h"
 #include "base64.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 
 #ifndef O_BINARY
@@ -2247,15 +2247,15 @@ int communicate(
     SSL_CTX_set_mode(ssl_ctx, SSL_MODE_AUTO_RETRY);
     SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
 
-    if (nghttp2::ssl::ssl_ctx_set_proto_versions(
-            ssl_ctx, nghttp2::ssl::NGHTTP2_TLS_MIN_VERSION,
-            nghttp2::ssl::NGHTTP2_TLS_MAX_VERSION) != 0) {
+    if (nghttp2::tls::ssl_ctx_set_proto_versions(
+            ssl_ctx, nghttp2::tls::NGHTTP2_TLS_MIN_VERSION,
+            nghttp2::tls::NGHTTP2_TLS_MAX_VERSION) != 0) {
       std::cerr << "[ERROR] Could not set TLS versions" << std::endl;
       result = -1;
       goto fin;
     }
 
-    if (SSL_CTX_set_cipher_list(ssl_ctx, ssl::DEFAULT_CIPHER_LIST) == 0) {
+    if (SSL_CTX_set_cipher_list(ssl_ctx, tls::DEFAULT_CIPHER_LIST) == 0) {
       std::cerr << "[ERROR] " << ERR_error_string(ERR_get_error(), nullptr)
                 << std::endl;
       result = -1;
@@ -2718,7 +2718,7 @@ Options:
 } // namespace
 
 int main(int argc, char **argv) {
-  ssl::libssl_init();
+  tls::libssl_init();
 
   bool color = false;
   while (1) {
diff --git a/src/nghttpd.cc b/src/nghttpd.cc
index 6080037b..b26aea2f 100644
--- a/src/nghttpd.cc
+++ b/src/nghttpd.cc
@@ -48,7 +48,7 @@
 #include "app_helper.h"
 #include "HttpServer.h"
 #include "util.h"
-#include "ssl.h"
+#include "tls.h"
 
 namespace nghttp2 {
 
@@ -190,10 +190,10 @@ Options:
 } // namespace
 
 int main(int argc, char **argv) {
-  ssl::libssl_init();
+  tls::libssl_init();
 
 #ifndef NOTHREADS
-  ssl::LibsslGlobalLock lock;
+  tls::LibsslGlobalLock lock;
 #endif // NOTHREADS
 
   Config config;
diff --git a/src/shrpx-unittest.cc b/src/shrpx-unittest.cc
index e53c1ac6..a5104afd 100644
--- a/src/shrpx-unittest.cc
+++ b/src/shrpx-unittest.cc
@@ -43,7 +43,7 @@
 #include "shrpx_http_test.h"
 #include "base64_test.h"
 #include "shrpx_config.h"
-#include "ssl.h"
+#include "tls.h"
 #include "shrpx_router_test.h"
 #include "shrpx_log.h"
 
@@ -55,7 +55,7 @@ int main(int argc, char *argv[]) {
   CU_pSuite pSuite = NULL;
   unsigned int num_tests_failed;
 
-  nghttp2::ssl::libssl_init();
+  nghttp2::tls::libssl_init();
 
   shrpx::create_config();
 
diff --git a/src/shrpx.cc b/src/shrpx.cc
index e0aca40f..15a961d2 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -88,7 +88,7 @@
 #include "shrpx_log.h"
 #include "util.h"
 #include "app_helper.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 #include "allocator.h"
 #include "ssl_compat.h"
@@ -1437,9 +1437,9 @@ void fill_default_config(Config *config) {
   }
 
   tlsconf.session_timeout = std::chrono::hours(12);
-  tlsconf.ciphers = StringRef::from_lit(nghttp2::ssl::DEFAULT_CIPHER_LIST);
+  tlsconf.ciphers = StringRef::from_lit(nghttp2::tls::DEFAULT_CIPHER_LIST);
   tlsconf.client.ciphers =
-      StringRef::from_lit(nghttp2::ssl::DEFAULT_CIPHER_LIST);
+      StringRef::from_lit(nghttp2::tls::DEFAULT_CIPHER_LIST);
   tlsconf.min_proto_version =
       ssl::proto_version_from_string(DEFAULT_TLS_MIN_PROTO_VERSION);
   tlsconf.max_proto_version =
@@ -3032,10 +3032,10 @@ int main(int argc, char **argv) {
   int rv;
   std::array<char, STRERROR_BUFSIZE> errbuf;
 
-  nghttp2::ssl::libssl_init();
+  nghttp2::tls::libssl_init();
 
 #ifndef NOTHREADS
-  nghttp2::ssl::LibsslGlobalLock lock;
+  nghttp2::tls::LibsslGlobalLock lock;
 #endif // NOTHREADS
 
   Log::set_severity_level(NOTICE);
diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index f46f5039..9260e9e3 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -56,7 +56,7 @@
 #endif // HAVE_SPDYLAY
 #include "util.h"
 #include "template.h"
-#include "ssl.h"
+#include "tls.h"
 
 using namespace nghttp2;
 
@@ -1202,7 +1202,7 @@ void ClientHandler::start_immediate_shutdown() {
 }
 
 void ClientHandler::write_accesslog(Downstream *downstream) {
-  nghttp2::ssl::TLSSessionInfo tls_info;
+  nghttp2::tls::TLSSessionInfo tls_info;
   auto &req = downstream->request();
 
   auto config = get_config();
@@ -1217,7 +1217,7 @@ void ClientHandler::write_accesslog(Downstream *downstream) {
       config->logging.access.format,
       LogSpec{
           downstream, ipaddr_, alpn_,
-          nghttp2::ssl::get_tls_session_info(&tls_info, conn_.tls.ssl),
+          nghttp2::tls::get_tls_session_info(&tls_info, conn_.tls.ssl),
           std::chrono::high_resolution_clock::now(), // request_end_time
           port_, faddr_->port, config->pid,
       });
diff --git a/src/shrpx_connection.cc b/src/shrpx_connection.cc
index 4a4ed14e..338e0f1c 100644
--- a/src/shrpx_connection.cc
+++ b/src/shrpx_connection.cc
@@ -502,8 +502,8 @@ int Connection::write_tls_pending_handshake() {
 
   if (LOG_ENABLED(INFO)) {
     LOG(INFO) << "SSL/TLS handshake completed";
-    nghttp2::ssl::TLSSessionInfo tls_info{};
-    if (nghttp2::ssl::get_tls_session_info(&tls_info, tls.ssl)) {
+    nghttp2::tls::TLSSessionInfo tls_info{};
+    if (nghttp2::tls::get_tls_session_info(&tls_info, tls.ssl)) {
       LOG(INFO) << "cipher=" << tls_info.cipher
                 << " protocol=" << tls_info.protocol
                 << " resumption=" << (tls_info.session_reused ? "yes" : "no")
@@ -530,7 +530,7 @@ int Connection::check_http2_requirement() {
       !util::check_h2_is_selected(StringRef{next_proto, next_proto_len})) {
     return 0;
   }
-  if (!nghttp2::ssl::check_http2_tls_version(tls.ssl)) {
+  if (!nghttp2::tls::check_http2_tls_version(tls.ssl)) {
     if (LOG_ENABLED(INFO)) {
       LOG(INFO) << "TLSv1.2 was not negotiated.  HTTP/2 must not be used.";
     }
@@ -545,7 +545,7 @@ int Connection::check_http2_requirement() {
   }
 
   if (check_black_list &&
-      nghttp2::ssl::check_http2_cipher_black_list(tls.ssl)) {
+      nghttp2::tls::check_http2_cipher_black_list(tls.ssl)) {
     if (LOG_ENABLED(INFO)) {
       LOG(INFO) << "The negotiated cipher suite is in HTTP/2 cipher suite "
                    "black list.  HTTP/2 must not be used.";
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index dafc9b0c..cdbb89b3 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -47,7 +47,7 @@
 #include "http2.h"
 #include "util.h"
 #include "base64.h"
-#include "ssl.h"
+#include "tls.h"
 
 using namespace nghttp2;
 
diff --git a/src/shrpx_live_check.cc b/src/shrpx_live_check.cc
index c478be25..2645d3e2 100644
--- a/src/shrpx_live_check.cc
+++ b/src/shrpx_live_check.cc
@@ -768,7 +768,7 @@ int LiveCheck::connection_made() {
   }
 
   auto must_terminate =
-      addr_->tls && !nghttp2::ssl::check_http2_requirement(conn_.tls.ssl);
+      addr_->tls && !nghttp2::tls::check_http2_requirement(conn_.tls.ssl);
 
   if (must_terminate) {
     if (LOG_ENABLED(INFO)) {
diff --git a/src/shrpx_log.h b/src/shrpx_log.h
index 1afb6e1a..61abb9e2 100644
--- a/src/shrpx_log.h
+++ b/src/shrpx_log.h
@@ -36,7 +36,7 @@
 
 #include "shrpx_config.h"
 #include "shrpx_log_config.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 
 using namespace nghttp2;
@@ -148,7 +148,7 @@ struct LogSpec {
   Downstream *downstream;
   StringRef remote_addr;
   StringRef alpn;
-  const nghttp2::ssl::TLSSessionInfo *tls_info;
+  const nghttp2::tls::TLSSessionInfo *tls_info;
   std::chrono::high_resolution_clock::time_point request_end_time;
   StringRef remote_port;
   uint16_t server_port;
diff --git a/src/shrpx_ssl.cc b/src/shrpx_ssl.cc
index b9ce118b..24b005a4 100644
--- a/src/shrpx_ssl.cc
+++ b/src/shrpx_ssl.cc
@@ -62,7 +62,7 @@
 #include "shrpx_memcached_dispatcher.h"
 #include "shrpx_connection_handler.h"
 #include "util.h"
-#include "ssl.h"
+#include "tls.h"
 #include "template.h"
 #include "ssl_compat.h"
 
@@ -687,7 +687,7 @@ SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file,
 
   SSL_CTX_set_options(ssl_ctx, ssl_opts | tlsconf.tls_proto_mask);
 
-  if (nghttp2::ssl::ssl_ctx_set_proto_versions(
+  if (nghttp2::tls::ssl_ctx_set_proto_versions(
           ssl_ctx, tlsconf.min_proto_version, tlsconf.max_proto_version) != 0) {
     LOG(FATAL) << "Could not set TLS protocol version";
     DIE();
@@ -934,7 +934,7 @@ SSL_CTX *create_ssl_client_context(
                                               SSL_SESS_CACHE_NO_INTERNAL_STORE);
   SSL_CTX_sess_set_new_cb(ssl_ctx, tls_session_client_new_cb);
 
-  if (nghttp2::ssl::ssl_ctx_set_proto_versions(
+  if (nghttp2::tls::ssl_ctx_set_proto_versions(
           ssl_ctx, tlsconf.min_proto_version, tlsconf.max_proto_version) != 0) {
     LOG(FATAL) << "Could not set TLS protocol version";
     DIE();
diff --git a/src/ssl.cc b/src/tls.cc
similarity index 99%
rename from src/ssl.cc
rename to src/tls.cc
index 8ad44b96..6920fe40 100644
--- a/src/ssl.cc
+++ b/src/tls.cc
@@ -22,7 +22,7 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "ssl.h"
+#include "tls.h"
 
 #include <cassert>
 #include <vector>
@@ -36,7 +36,7 @@
 
 namespace nghttp2 {
 
-namespace ssl {
+namespace tls {
 
 #if OPENSSL_1_1_API
 
@@ -196,6 +196,6 @@ int ssl_ctx_set_proto_versions(SSL_CTX *ssl_ctx, int min, int max) {
 #endif // !OPENSSL_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
 }
 
-} // namespace ssl
+} // namespace tls
 
 } // namespace nghttp2
diff --git a/src/ssl.h b/src/tls.h
similarity index 98%
rename from src/ssl.h
rename to src/tls.h
index 845aa2fe..8aa618d5 100644
--- a/src/ssl.h
+++ b/src/tls.h
@@ -22,8 +22,8 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#ifndef SSL_H
-#define SSL_H
+#ifndef TLS_H
+#define TLS_H
 
 #include "nghttp2_config.h"
 
@@ -33,7 +33,7 @@
 
 namespace nghttp2 {
 
-namespace ssl {
+namespace tls {
 
 // Acquire OpenSSL global lock to share SSL_CTX across multiple
 // threads. The constructor acquires lock and destructor unlocks.
@@ -113,8 +113,8 @@ void libssl_init();
 // 0 if it succeeds, or -1.
 int ssl_ctx_set_proto_versions(SSL_CTX *ssl_ctx, int min, int max);
 
-} // namespace ssl
+} // namespace tls
 
 } // namespace nghttp2
 
-#endif // SSL_H
+#endif // TLS_H