diff --git a/src/ngx_http_lua_socket_tcp.c b/src/ngx_http_lua_socket_tcp.c
index 964774041e..10aa7e9678 100644
--- a/src/ngx_http_lua_socket_tcp.c
+++ b/src/ngx_http_lua_socket_tcp.c
@@ -970,8 +970,16 @@ ngx_http_lua_socket_tcp_connect(lua_State *L)
         n--;
     }
 
-    if (n == 3) {
-        port = luaL_checkinteger(L, 3);
+    /* most popular suit: host:port */
+    if (n == 3 && lua_isnumber(L, 3)) {
+
+        /* Hit the following parameter combination:
+         * sock:connect("127.0.0.1", port)
+         * sock:connect("127.0.0.1", port, opts)
+         * sock:connect("unix:/path", port)
+         * sock:connect("unix:/path", port, opts) */
+
+        port = (int) lua_tointeger(L, 3);
 
         if (port < 0 || port > 65535) {
             lua_pushnil(L);
@@ -987,8 +995,27 @@ ngx_http_lua_socket_tcp_connect(lua_State *L)
 
         dd("socket key: %s", lua_tostring(L, -1));
 
-    } else { /* n == 2 */
+    } else if (len >= 5 && ngx_strncasecmp(p, (u_char *) "unix:", 5) == 0) {
+
+        /* Hit the following parameter combination:
+         * sock:connect("unix:/path")
+         * sock:connect("unix:/path", nil)
+         * sock:connect("unix:/path", opts)
+         * sock:connect("unix:/path", nil, opts) */
+
         port = 0;
+
+    } else {
+
+        /* Ban the following parameter combination:
+         * sock:connect("127.0.0.1")
+         * sock:connect("127.0.0.1", nil)
+         * sock:connect("127.0.0.1", opts) 
+         * sock:connect("127.0.0.1", nil, opts) */
+
+        lua_pushnil(L);
+        lua_pushfstring(L, "missing the port number");
+        return 2;
     }
 
     if (!custom_pool) {
diff --git a/t/023-rewrite/unix-socket.t b/t/023-rewrite/unix-socket.t
index 8a5f00019b..91826fc3eb 100644
--- a/t/023-rewrite/unix-socket.t
+++ b/t/023-rewrite/unix-socket.t
@@ -79,7 +79,7 @@ qr{\[crit\] .*? connect\(\) to unix:/tmp/nosuchfile\.sock failed}
 --- request
     GET /test
 --- response_body
-failed to connect: failed to parse host name "/tmp/test-nginx.sock": invalid host
+failed to connect: missing the port number
 
 
 
diff --git a/t/058-tcp-socket.t b/t/058-tcp-socket.t
index cac464d830..593e49461f 100644
--- a/t/058-tcp-socket.t
+++ b/t/058-tcp-socket.t
@@ -4,7 +4,7 @@ use Test::Nginx::Socket::Lua;
 
 repeat_each(2);
 
-plan tests => repeat_each() * 228;
+plan tests => repeat_each() * 231;
 
 our $HtmlDir = html_dir;
 
@@ -3029,7 +3029,7 @@ qr/runtime error: content_by_lua\(nginx\.conf:\d+\):16: bad request/
 --- user_files
 >>> myfoo.lua
 local sock = ngx.socket.tcp()
-local ok, err = sock:connect("agentzh.org")
+local ok, err = sock:connect("agentzh.org", 12345)
 if not ok then
     ngx.log(ngx.ERR, "failed to connect: ", err)
     return
@@ -3059,7 +3059,7 @@ runtime error: attempt to yield across C-call boundary
             end
             local function err()
                 local sock = ngx.socket.tcp()
-                local ok, err = sock:connect("agentzh.org")
+                local ok, err = sock:connect("agentzh.org", 12345)
                 if not ok then
                     ngx.log(ngx.ERR, "failed to connect: ", err)
                     return
@@ -4327,3 +4327,43 @@ failed to receive a line: closed []
 close: 1 nil
 --- no_error_log
 [error]
+
+
+
+=== TEST 72: port is not number
+--- config
+    server_tokens off;
+    location = /t {
+        set $port $TEST_NGINX_SERVER_PORT;
+        content_by_lua_block {
+            local sock = ngx.socket.tcp()
+            sock:settimeout(500)
+
+            local ok, err = sock:connect("127.0.0.1")
+            if not ok then
+                ngx.say("connect failed: ", err)
+            end
+
+            local ok, err = sock:connect("127.0.0.1", nil)
+            if not ok then
+                ngx.say("connect failed: ", err)
+            end
+
+            local ok, err = sock:connect("127.0.0.1", {})
+            if not ok then
+                ngx.say("connect failed: ", err)
+            end
+
+            ngx.say("finish")
+        }
+    }
+
+--- request
+GET /t
+--- response_body
+connect failed: missing the port number
+connect failed: missing the port number
+connect failed: missing the port number
+finish
+--- no_error_log
+[error]
diff --git a/t/059-unix-socket.t b/t/059-unix-socket.t
index b06ba6e2ee..bd83006baf 100644
--- a/t/059-unix-socket.t
+++ b/t/059-unix-socket.t
@@ -64,7 +64,7 @@ qr{\[crit\] .*? connect\(\) to unix:/tmp/nosuchfile\.sock failed}
 --- request
     GET /test
 --- response_body
-failed to connect: failed to parse host name "/tmp/test-nginx.sock": invalid host
+failed to connect: missing the port number
 
 
 
@@ -201,3 +201,139 @@ received:
 received: foo
 failed to receive a line: closed
 close: 1 nil
+
+
+
+=== TEST 5: port will be ignored
+--- http_config
+    server {
+        listen unix:$TEST_NGINX_HTML_DIR/nginx.sock;
+        default_type 'text/plain';
+
+        server_tokens off;
+        location /foo {
+            content_by_lua 'ngx.say("foo")';
+            more_clear_headers Date;
+        }
+    }
+--- config
+    location /test {
+        content_by_lua '
+            local sock = ngx.socket.tcp()
+            local ok, err = sock:connect("unix:$TEST_NGINX_HTML_DIR/nginx.sock", 80)
+            if not ok then
+                ngx.say("failed to connect: ", err)
+                return
+            end
+
+            ngx.say("connected: ", ok)
+
+            local req = "GET /foo HTTP/1.0\\r\\nHost: localhost\\r\\nConnection: close\\r\\n\\r\\n"
+            -- req = "OK"
+
+            local bytes, err = sock:send(req)
+            if not bytes then
+                ngx.say("failed to send request: ", err)
+                return
+            end
+
+            ngx.say("request sent: ", bytes)
+
+            while true do
+                print("calling receive")
+                local line, err = sock:receive()
+                if line then
+                    ngx.say("received: ", line)
+
+                else
+                    ngx.say("failed to receive a line: ", err)
+                    break
+                end
+            end
+
+            ok, err = sock:close()
+            ngx.say("close: ", ok, " ", err)
+        ';
+    }
+--- request
+    GET /test
+--- response_body
+connected: 1
+request sent: 57
+received: HTTP/1.1 200 OK
+received: Server: nginx
+received: Content-Type: text/plain
+received: Content-Length: 4
+received: Connection: close
+received: 
+received: foo
+failed to receive a line: closed
+close: 1 nil
+
+
+
+=== TEST 6: second parameter is nil
+--- http_config
+    server {
+        listen unix:$TEST_NGINX_HTML_DIR/nginx.sock;
+        default_type 'text/plain';
+
+        server_tokens off;
+        location /foo {
+            content_by_lua 'ngx.say("foo")';
+            more_clear_headers Date;
+        }
+    }
+--- config
+    location /test {
+        content_by_lua '
+            local sock = ngx.socket.tcp()
+            local ok, err = sock:connect("unix:$TEST_NGINX_HTML_DIR/nginx.sock", nil)
+            if not ok then
+                ngx.say("failed to connect: ", err)
+                return
+            end
+
+            ngx.say("connected: ", ok)
+
+            local req = "GET /foo HTTP/1.0\\r\\nHost: localhost\\r\\nConnection: close\\r\\n\\r\\n"
+            -- req = "OK"
+
+            local bytes, err = sock:send(req)
+            if not bytes then
+                ngx.say("failed to send request: ", err)
+                return
+            end
+
+            ngx.say("request sent: ", bytes)
+
+            while true do
+                print("calling receive")
+                local line, err = sock:receive()
+                if line then
+                    ngx.say("received: ", line)
+
+                else
+                    ngx.say("failed to receive a line: ", err)
+                    break
+                end
+            end
+
+            ok, err = sock:close()
+            ngx.say("close: ", ok, " ", err)
+        ';
+    }
+--- request
+    GET /test
+--- response_body
+connected: 1
+request sent: 57
+received: HTTP/1.1 200 OK
+received: Server: nginx
+received: Content-Type: text/plain
+received: Content-Length: 4
+received: Connection: close
+received: 
+received: foo
+failed to receive a line: closed
+close: 1 nil
diff --git a/t/068-socket-keepalive.t b/t/068-socket-keepalive.t
index e4c698887b..d67da3bd1e 100644
--- a/t/068-socket-keepalive.t
+++ b/t/068-socket-keepalive.t
@@ -4,7 +4,7 @@ use Test::Nginx::Socket::Lua;
 
 #repeat_each(2);
 
-plan tests => repeat_each() * (blocks() * 4 + 31);
+plan tests => repeat_each() * (blocks() * 4 + 34);
 
 our $HtmlDir = html_dir;
 
@@ -2956,3 +2956,63 @@ GET /t
 lua tcp socket abort queueing
 --- response_body
 ok
+
+
+
+=== TEST 53: custom pools in third parameters for unix domain socket
+--- http_config eval
+"
+    lua_package_path '$::HtmlDir/?.lua;./?.lua;;';
+    server {
+        listen unix:$::HtmlDir/nginx.sock;
+        default_type 'text/plain';
+
+        server_tokens off;
+        location /foo {
+            echo foo;
+            more_clear_headers Date;
+        }
+    }
+"
+--- config
+    location /t {
+        set $port $TEST_NGINX_MEMCACHED_PORT;
+        content_by_lua '
+            local test = require "test"
+            local path = "$TEST_NGINX_HTML_DIR/nginx.sock";
+            test.go(path, "A")
+            test.go(path, "B")
+        ';
+    }
+--- user_files
+>>> test.lua
+module("test", package.seeall)
+
+function go(path, pool)
+    local sock = ngx.socket.tcp()
+    local ok, err = sock:connect("unix:" .. path, nil, {pool = pool})
+    if not ok then
+        ngx.say("failed to connect: ", err)
+        return
+    end
+
+    ngx.say("connected: ", ok, ", reused: ", sock:getreusedtimes())
+
+    local ok, err = sock:setkeepalive()
+    if not ok then
+        ngx.say("failed to set reusable: ", err)
+    end
+end
+--- request
+GET /t
+--- response_body
+connected: 1, reused: 0
+connected: 1, reused: 0
+--- no_error_log eval
+["[error]",
+"lua tcp socket keepalive: free connection pool for ",
+"lua tcp socket get keepalive peer: using connection"
+]
+--- error_log
+lua tcp socket keepalive create connection pool for key "A"
+lua tcp socket keepalive create connection pool for key "B"