diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 92167d7..366ab3e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,7 +9,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: goto-bus-stop/setup-zig@v2
         with:
-          version: master
+          version: 0.12.0
       - run: zig fmt --check *.zig src/*.zig
 
   test:
@@ -21,7 +21,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: goto-bus-stop/setup-zig@v2
         with:
-          version: master
+          version: 0.12.0
       - run: zig build test
 
   macos-with-openssl:
diff --git a/README.md b/README.md
index ef56b98..b12f941 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # tls13-zig
 
-The first TLS1.3 implementation in Zig(master/HEAD) only with std.
+The first TLS1.3 implementation in Zig(0.12.0) only with std.
 
 
 This repository is an experimental implementation and is not intended for production use.
diff --git a/examples/proxy/build.zig b/examples/proxy/build.zig
index c23b48e..db493f2 100644
--- a/examples/proxy/build.zig
+++ b/examples/proxy/build.zig
@@ -18,8 +18,9 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
     });
-    exe.addAnonymousModule("tls13-server", .{
-        .source_file = .{ .path = "../../src/server.zig" },
+
+    exe.root_module.addAnonymousImport("tls13-server", .{
+        .root_source_file = .{ .path = "../../src/server.zig" },
     });
     // This declares intent for the executable to be installed into the
     // standard location when the user invokes the "install" step (the default
diff --git a/examples/proxy/src/main.zig b/examples/proxy/src/main.zig
index 5083b05..e5b1de7 100644
--- a/examples/proxy/src/main.zig
+++ b/examples/proxy/src/main.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 const net = std.net;
 const io = std.io;
-const os = std.os;
+const posix = std.posix;
 const allocator = std.heap.page_allocator;
 
 const server = @import("tls13-server");
@@ -9,12 +9,12 @@ const log = server.log;
 
 pub fn main() !void {
     // ignore SIGCHLD
-    var act = os.Sigaction{
-        .handler = .{ .handler = os.SIG.IGN },
-        .mask = os.empty_sigset,
-        .flags = (os.SA.SIGINFO | os.SA.RESTART | os.SA.RESETHAND),
+    var act = posix.Sigaction{
+        .handler = .{ .handler = posix.SIG.IGN },
+        .mask = posix.empty_sigset,
+        .flags = (posix.SA.SIGINFO | posix.SA.RESTART | posix.SA.RESETHAND),
     };
-    try os.sigaction(os.SIG.CHLD, &act, null);
+    try posix.sigaction(posix.SIG.CHLD, &act, null);
 
     const key_file = try getenvWithError("PROXY_TLS_KEYFILE");
     const cert_file = try getenvWithError("PROXY_TLS_CERTFILE");
@@ -34,7 +34,7 @@ pub fn main() !void {
     while (true) {
         var con = try tls_server.accept();
         defer con.deinit();
-        const fork_pid = std.os.fork() catch {
+        const fork_pid = posix.fork() catch {
             log.err("fork failed", .{});
             return;
         };
@@ -55,15 +55,15 @@ pub fn main() !void {
         var conStream = try net.tcpConnectToHost(allocator, upstream_host, upstream_port);
         defer conStream.close();
 
-        var fds: [2]std.os.pollfd = undefined;
+        var fds: [2]posix.pollfd = undefined;
         fds[0] = .{
             .fd = con.tcp_conn.?.stream.handle,
-            .events = std.os.POLL.IN,
+            .events = posix.POLL.IN,
             .revents = undefined,
         };
         fds[1] = .{
             .fd = conStream.handle,
-            .events = std.os.POLL.IN,
+            .events = posix.POLL.IN,
             .revents = undefined,
         };
 
@@ -71,12 +71,12 @@ pub fn main() !void {
         var req_done = false;
         var sendBuf = std.io.bufferedWriter(conStream.writer());
         while (true) {
-            _ = try std.os.poll(&fds, -1);
+            _ = try posix.poll(&fds, -1);
             log.debug("poll done", .{});
             var recv_bytes: [16 * 1024]u8 = undefined;
             var tmp_buf: [16 * 1024]u8 = undefined;
 
-            if ((fds[0].revents & std.os.POLL.IN) > 0) {
+            if ((fds[0].revents & posix.POLL.IN) > 0) {
                 while (true) {
                     const line = con.tlsReader().readUntilDelimiter(&tmp_buf, '\n') catch |err| {
                         log.err("failed to read({})", .{err});
@@ -116,7 +116,7 @@ pub fn main() !void {
                     try sendBuf.flush();
                     req_done = false;
                 }
-            } else if ((fds[1].revents & std.os.POLL.IN) > 0) {
+            } else if ((fds[1].revents & posix.POLL.IN) > 0) {
                 const recv_size = try conStream.read(&recv_bytes);
                 if (recv_size == 0) {
                     log.info("upstream connection closed", .{});
@@ -133,7 +133,7 @@ pub fn main() !void {
 }
 
 fn getenvWithError(key: []const u8) ![]const u8 {
-    const res = std.os.getenv(key);
+    const res = posix.getenv(key);
     if (res) |r| {
         return r;
     } else {
diff --git a/install_zig.sh b/install_zig.sh
index 98bd59b..35113e4 100755
--- a/install_zig.sh
+++ b/install_zig.sh
@@ -10,18 +10,19 @@ case "$unames" in
     *)          echo "Unknown HOST_ARCH=$(uname -s)"; exit 1;;
 esac
 
+ZIG_VERSION=0.12.0
 ZIG_VERSIONS=$(curl https://ziglang.org/download/index.json)
 
-ZIG_MASTER_TAR=$(echo $ZIG_VERSIONS | jq -r ".master.\"$HOST_ARCH\".tarball")
-ZIG_MASTER_SHA256=$(echo $ZIG_VERSIONS | jq -r ".master.\"$HOST_ARCH\".shasum")
+ZIG_MASTER_TAR=$(echo $ZIG_VERSIONS | jq -r ".\"$ZIG_VERSION\".\"$HOST_ARCH\".tarball")
+ZIG_MASTER_SHA256=$(echo $ZIG_VERSIONS | jq -r ".\"$ZIG_VERSION\".\"$HOST_ARCH\".shasum")
 
-ZIG_TAR_NAME="zig-master.tar.xz"
+ZIG_TAR_NAME="zig-$ZIG_VERSION.tar.xz"
 
 if [ -e $ZIG_TAR_NAME ]; then
     rm $ZIG_TAR_NAME
 fi
 
-curl $ZIG_MASTER_TAR -o zig-master.tar.xz
+curl $ZIG_MASTER_TAR -o $ZIG_TAR_NAME 
 TAR_SHA256=$(shasum -a 256 $ZIG_TAR_NAME | awk '{print $1}')
 if [ "$TAR_SHA256" != "$ZIG_MASTER_SHA256" ]; then
     echo "Invalid SHASUM!"
diff --git a/src/client.zig b/src/client.zig
index d415c89..59f2271 100644
--- a/src/client.zig
+++ b/src/client.zig
@@ -254,7 +254,7 @@ pub fn TLSClientImpl(comptime ReaderType: type, comptime WriterType: type, compt
                 p.deinit();
             }
             if (self.tcp_client) |tc| {
-                std.os.shutdown(tc.handle, .both) catch |err| {
+                std.posix.shutdown(tc.handle, .both) catch |err| {
                     log.warn("failed to shutdown tcp client err={}", .{err});
                 };
             }
@@ -373,7 +373,7 @@ pub fn TLSClientImpl(comptime ReaderType: type, comptime WriterType: type, compt
             if (list.addrs.len == 0) return error.UnknownHostName;
 
             for (list.addrs) |addr| {
-                if (addr.any.family != std.os.AF.INET) {
+                if (addr.any.family != std.posix.AF.INET) {
                     continue;
                 }
                 // TODO: ipv6
@@ -391,7 +391,7 @@ pub fn TLSClientImpl(comptime ReaderType: type, comptime WriterType: type, compt
 
                 return;
             }
-            return std.os.ConnectError.ConnectionRefused;
+            return std.posix.ConnectError.ConnectionRefused;
         }
 
         pub fn connect(self: *Self, host: []const u8, port: u16) !void {
@@ -531,7 +531,7 @@ pub fn TLSClientImpl(comptime ReaderType: type, comptime WriterType: type, compt
         pub fn close(self: *Self) !void {
             defer {
                 if (self.tcp_client) |tc| {
-                    std.os.shutdown(tc.handle, .both) catch {
+                    std.posix.shutdown(tc.handle, .both) catch {
                         //TODO Error handle
                     };
                 }
diff --git a/src/main_test_server.zig b/src/main_test_server.zig
index 70bace4..ce86a2a 100644
--- a/src/main_test_server.zig
+++ b/src/main_test_server.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const log = @import("log.zig");
-const os = std.os;
+const posix = std.posix;
 
 const server = @import("server.zig");
 
@@ -15,12 +15,12 @@ fn handler_sigchld(signum: c_int) callconv(.C) void {
 
 pub fn do(fork: bool, allocator: std.mem.Allocator) !void {
     // ignore SIGCHLD
-    var act = os.Sigaction{
+    var act = posix.Sigaction{
         .handler = .{ .handler = handler_sigchld },
-        .mask = os.empty_sigset,
-        .flags = (os.SA.SIGINFO | os.SA.RESTART | os.SA.RESETHAND),
+        .mask = posix.empty_sigset,
+        .flags = (posix.SA.SIGINFO | posix.SA.RESTART | posix.SA.RESETHAND),
     };
-    try os.sigaction(os.SIG.CHLD, &act, null);
+    try posix.sigaction(posix.SIG.CHLD, &act, null);
 
     log.info("started.", .{});
 
@@ -41,7 +41,7 @@ pub fn do(fork: bool, allocator: std.mem.Allocator) !void {
         var con = try tls_server.accept();
         defer con.deinit();
         if (fork) {
-            const fork_pid = std.os.fork() catch {
+            const fork_pid = std.posix.fork() catch {
                 log.err("fork failed", .{});
                 return;
             };
diff --git a/src/server.zig b/src/server.zig
index 3ea39f2..4955dce 100644
--- a/src/server.zig
+++ b/src/server.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const io = std.io;
-const os = std.os;
+const posix = std.posix;
 const net = std.net;
 const dh = std.crypto.dh;
 const expect = std.testing.expect;
@@ -58,7 +58,7 @@ pub fn TLSServerImpl(comptime ReaderType: type, comptime WriterType: type, compt
     _ = WriterType;
     return struct {
         // io
-        tcp_listener: ?std.net.StreamServer = null,
+        tcp_listener: ?std.net.Server = null,
 
         // host
         host: []u8 = &([_]u8{}),
@@ -95,12 +95,12 @@ pub fn TLSServerImpl(comptime ReaderType: type, comptime WriterType: type, compt
 
         pub fn init(key_path: []const u8, cert_path: []const u8, ca_path: ?[]const u8, host: ?[]const u8, allocator: std.mem.Allocator) !Self {
             // ignore SIGPIPE
-            var act = os.Sigaction{
-                .handler = .{ .handler = os.SIG.IGN },
-                .mask = os.empty_sigset,
-                .flags = (os.SA.SIGINFO | os.SA.RESTART | os.SA.RESETHAND),
+            var act = posix.Sigaction{
+                .handler = .{ .handler = posix.SIG.IGN },
+                .mask = posix.empty_sigset,
+                .flags = (posix.SA.SIGINFO | posix.SA.RESTART | posix.SA.RESETHAND),
             };
-            try os.sigaction(os.SIG.PIPE, &act, null);
+            try posix.sigaction(posix.SIG.PIPE, &act, null);
 
             const cert = try certificate.CertificateEntry.fromFile(cert_path, allocator);
             errdefer cert.deinit();
@@ -146,17 +146,12 @@ pub fn TLSServerImpl(comptime ReaderType: type, comptime WriterType: type, compt
                 @memcpy(res.host, h);
             }
 
-            if (is_tcp) {
-                res.tcp_listener = std.net.StreamServer.init(.{});
-                res.tcp_listener.?.reuse_address = true;
-            }
-
             return res;
         }
 
         pub fn deinit(self: *Self) void {
             if (self.tcp_listener) |_| {
-                self.tcp_listener.?.close();
+                self.tcp_listener.?.deinit();
             }
             if (self.host.len != 0) {
                 self.allocator.free(self.host);
@@ -171,7 +166,9 @@ pub fn TLSServerImpl(comptime ReaderType: type, comptime WriterType: type, compt
 
         pub fn listen(self: *Self, port: u16) !void {
             if (is_tcp) {
-                try self.tcp_listener.?.listen(try std.net.Address.parseIp("0.0.0.0", port));
+                const listen_addr = try std.net.Address.parseIp("0.0.0.0", port);
+                const listen_opts = std.net.Address.ListenOptions{ .reuse_address = true };
+                self.tcp_listener = try listen_addr.listen(listen_opts);
             }
         }
 
@@ -199,7 +196,7 @@ pub fn TLSStreamImpl(comptime ReaderType: type, comptime WriterType: type, compt
         reader: ReaderType,
         writer: WriterType,
         write_buffer: io.BufferedWriter(4096, WriterType),
-        tcp_conn: ?std.net.StreamServer.Connection = null,
+        tcp_conn: ?std.net.Server.Connection = null,
 
         // session related
         random: [32]u8,
@@ -275,7 +272,7 @@ pub fn TLSStreamImpl(comptime ReaderType: type, comptime WriterType: type, compt
             return .{ .context = self };
         }
 
-        pub fn init(server: TLSServerType, tcp_conn: std.net.StreamServer.Connection, allocator: std.mem.Allocator) !Self {
+        pub fn init(server: TLSServerType, tcp_conn: std.net.Server.Connection, allocator: std.mem.Allocator) !Self {
             if (!is_tcp) {
                 return Error.NotTCP;
             }
diff --git a/src/utils.zig b/src/utils.zig
index 276168f..be2669a 100644
--- a/src/utils.zig
+++ b/src/utils.zig
@@ -27,10 +27,10 @@ test "intToEnum" {
 }
 
 pub fn setReadTimeout(self: std.net.Stream, milliseconds: usize) !void {
-    const timeout = std.os.timeval{
+    const timeout = std.posix.timeval{
         .tv_sec = @as(i32, @intCast(milliseconds / std.time.ms_per_s)),
         .tv_usec = @as(i32, @intCast((milliseconds % std.time.ms_per_s) * std.time.us_per_ms)),
     };
 
-    return std.os.setsockopt(self.handle, std.os.SOL.SOCKET, std.os.SO.RCVTIMEO, std.mem.asBytes(&timeout));
+    return std.posix.setsockopt(self.handle, std.posix.SOL.SOCKET, std.posix.SO.RCVTIMEO, std.mem.asBytes(&timeout));
 }