diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2ca33457..349ba566 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -82,8 +82,8 @@ if (EMSCRIPTEN)
   set(ZLIB_LIBRARIES)
   set(ZLIB_INCLUDE_DIR)
 
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s WEBSOCKET_URL=\"'wss:#'\" -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Os -s ALLOW_MEMORY_GROWTH=1 -s USE_ZLIB=1 -s MODULARIZE=1 -s WEBSOCKET_URL=\"'wss:#'\" -s EXTRA_EXPORTED_RUNTIME_METHODS=\"['FS']\"")
   set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -s DEMANGLE_SUPPORT=1 -s ASSERTIONS=1")
   set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -s DEMANGLE_SUPPORT=1 -s ASSERTIONS=1")
 
diff --git a/td/telegram/net/ConnectionCreator.cpp b/td/telegram/net/ConnectionCreator.cpp
index b0081c1f..297b2112 100644
--- a/td/telegram/net/ConnectionCreator.cpp
+++ b/td/telegram/net/ConnectionCreator.cpp
@@ -1263,14 +1263,22 @@ void ConnectionCreator::hangup() {
 
 DcOptions ConnectionCreator::get_default_dc_options(bool is_test) {
   DcOptions res;
-  auto add_ip_ports = [&res](int32 dc_id, const vector<string> &ips, const vector<int> &ports, bool is_ipv6 = false) {
+  enum class HostType { IPv4, IPv6, Url };
+  auto add_ip_ports = [&res](int32 dc_id, const vector<string> &ips, const vector<int> &ports,
+                             HostType type = HostType::IPv4) {
     IPAddress ip_address;
     for (auto &ip : ips) {
       for (auto port : ports) {
-        if (is_ipv6) {
-          ip_address.init_ipv6_port(ip, port).ensure();
-        } else {
-          ip_address.init_ipv4_port(ip, port).ensure();
+        switch (type) {
+          case HostType::IPv4:
+            ip_address.init_ipv4_port(ip, port).ensure();
+            break;
+          case HostType::IPv6:
+            ip_address.init_ipv6_port(ip, port).ensure();
+            break;
+          case HostType::Url:
+            ip_address.init_host_port(ip, port).ensure();
+            break;
         }
         res.dc_options.emplace_back(DcId::internal(dc_id), ip_address);
       }
@@ -1282,9 +1290,9 @@ DcOptions ConnectionCreator::get_default_dc_options(bool is_test) {
     add_ip_ports(2, {"149.154.167.40"}, ports);
     add_ip_ports(3, {"149.154.175.117"}, ports);
 
-    add_ip_ports(1, {"2001:b28:f23d:f001::e"}, ports, true);
-    add_ip_ports(2, {"2001:67c:4e8:f002::e"}, ports, true);
-    add_ip_ports(3, {"2001:b28:f23d:f003::e"}, ports, true);
+    add_ip_ports(1, {"2001:b28:f23d:f001::e"}, ports, HostType::IPv6);
+    add_ip_ports(2, {"2001:67c:4e8:f002::e"}, ports, HostType::IPv6);
+    add_ip_ports(3, {"2001:b28:f23d:f003::e"}, ports, HostType::IPv6);
   } else {
     add_ip_ports(1, {"149.154.175.50"}, ports);
     add_ip_ports(2, {"149.154.167.51"}, ports);
@@ -1292,11 +1300,11 @@ DcOptions ConnectionCreator::get_default_dc_options(bool is_test) {
     add_ip_ports(4, {"149.154.167.91"}, ports);
     add_ip_ports(5, {"149.154.171.5"}, ports);
 
-    add_ip_ports(1, {"2001:b28:f23d:f001::a"}, ports, true);
-    add_ip_ports(2, {"2001:67c:4e8:f002::a"}, ports, true);
-    add_ip_ports(3, {"2001:b28:f23d:f003::a"}, ports, true);
-    add_ip_ports(4, {"2001:67c:4e8:f004::a"}, ports, true);
-    add_ip_ports(5, {"2001:b28:f23f:f005::a"}, ports, true);
+    add_ip_ports(1, {"2001:b28:f23d:f001::a"}, ports, HostType::IPv6);
+    add_ip_ports(2, {"2001:67c:4e8:f002::a"}, ports, HostType::IPv6);
+    add_ip_ports(3, {"2001:b28:f23d:f003::a"}, ports, HostType::IPv6);
+    add_ip_ports(4, {"2001:67c:4e8:f004::a"}, ports, HostType::IPv6);
+    add_ip_ports(5, {"2001:b28:f23f:f005::a"}, ports, HostType::IPv6);
   }
   return res;
 }