diff --git a/internal/app/appbase/flags.go b/internal/app/appbase/flags.go
index 630632af..6092e3fe 100644
--- a/internal/app/appbase/flags.go
+++ b/internal/app/appbase/flags.go
@@ -8,6 +8,14 @@ import (
 	"wa-lang.org/wa/internal/config"
 )
 
+// wabt工具
+func MakeFlag_wabt() *cli.BoolFlag {
+	return &cli.BoolFlag{
+		Name:  "wabt",
+		Usage: "use wabt/wat2wasm tool",
+	}
+}
+
 // 输出路径
 func MakeFlag_output() *cli.StringFlag {
 	return &cli.StringFlag{
diff --git a/internal/app/appbase/opt.go b/internal/app/appbase/opt.go
index 39d4e848..c7d8e1fb 100644
--- a/internal/app/appbase/opt.go
+++ b/internal/app/appbase/opt.go
@@ -13,6 +13,7 @@ import (
 
 // 命令行选项
 type Option struct {
+	UseWabt      bool
 	Debug        bool
 	WaBackend    string
 	BuilgTags    []string
@@ -80,6 +81,10 @@ func BuildOptions(c *cli.Context, waBackend ...string) *Option {
 		LD_MaxMemory: c.Int("ld-max-memory"),
 	}
 
+	if c.Bool("wabt") {
+		opt.UseWabt = true
+	}
+
 	opt.TargetArch = "wasm"
 	if len(waBackend) > 0 {
 		opt.WaBackend = waBackend[0]
diff --git a/internal/app/appbuild/appbuild.go b/internal/app/appbuild/appbuild.go
index 15938466..802cc3aa 100644
--- a/internal/app/appbuild/appbuild.go
+++ b/internal/app/appbuild/appbuild.go
@@ -13,12 +13,14 @@ import (
 	"wa-lang.org/wa/internal/config"
 	"wa-lang.org/wa/internal/loader"
 	"wa-lang.org/wa/internal/wabt"
+	"wa-lang.org/wa/internal/wat/watutil"
 )
 
 var CmdBuild = &cli.Command{
 	Name:  "build",
 	Usage: "compile Wa source code",
 	Flags: []cli.Flag{
+		appbase.MakeFlag_wabt(),
 		appbase.MakeFlag_output(),
 		appbase.MakeFlag_target(),
 		appbase.MakeFlag_tags(),
@@ -75,7 +77,7 @@ func BuildApp(opt *appbase.Option, input, outfile string) (mainFunc string, wasm
 			fmt.Printf("read %s failed: %v\n", input, err)
 			os.Exit(1)
 		}
-		wasmBytes, err := wabt.Wat2Wasm(watData)
+		wasmBytes, err := wat2wasm(opt.UseWabt, input, watData)
 		if err != nil {
 			fmt.Printf("wat2wasm %s failed: %v\n", input, err)
 			os.Exit(1)
@@ -114,7 +116,7 @@ func BuildApp(opt *appbase.Option, input, outfile string) (mainFunc string, wasm
 		}
 
 		// wat 编译为 wasm
-		wasmBytes, err := wabt.Wat2Wasm(watOutput)
+		wasmBytes, err := wat2wasm(opt.UseWabt, watOutfile, watOutput)
 		if err != nil {
 			fmt.Printf("wat2wasm %s failed: %v\n", input, err)
 			os.Exit(1)
@@ -196,7 +198,7 @@ func BuildApp(opt *appbase.Option, input, outfile string) (mainFunc string, wasm
 		}
 
 		// wat 编译为 wasm
-		wasmBytes, err := wabt.Wat2Wasm(watOutput)
+		wasmBytes, err := wat2wasm(opt.UseWabt, input, watOutput)
 		if err != nil {
 			fmt.Printf("wat2wasm %s failed: %v\n", input, err)
 			os.Exit(1)
@@ -217,6 +219,14 @@ func BuildApp(opt *appbase.Option, input, outfile string) (mainFunc string, wasm
 	}
 }
 
+func wat2wasm(useWabt bool, filename string, watBytes []byte) (wasmBytes []byte, err error) {
+	if useWabt {
+		return wabt.Wat2Wasm(watBytes)
+	} else {
+		return watutil.Wat2Wasm(filename, watBytes)
+	}
+}
+
 func buildWat(opt *appbase.Option, filename string) (
 	prog *loader.Program, compiler *compiler_wat.Compiler,
 	watBytes []byte, err error,
diff --git a/internal/app/apprun/apprun.go b/internal/app/apprun/apprun.go
index ce1bd8f6..c2c54d44 100644
--- a/internal/app/apprun/apprun.go
+++ b/internal/app/apprun/apprun.go
@@ -25,6 +25,7 @@ var CmdRun = &cli.Command{
 	Name:  "run",
 	Usage: "compile and run Wa program",
 	Flags: []cli.Flag{
+		appbase.MakeFlag_wabt(),
 		appbase.MakeFlag_target(),
 		appbase.MakeFlag_tags(),
 		&cli.BoolFlag{
diff --git a/internal/wabt/wat2wasm_test.go b/internal/wabt/wat2wasm_test.go
index 6ac3ab8f..25bf188f 100644
--- a/internal/wabt/wat2wasm_test.go
+++ b/internal/wabt/wat2wasm_test.go
@@ -48,15 +48,6 @@ var watTests = []struct {
 	watCode string
 	errMsg  string
 }{
-	{
-		watCode: ``,
-		errMsg:  `error: unexpected token "EOF", expected a module field or a module.`,
-	},
-	{
-		watCode: `()`,
-		errMsg:  `error: unexpected token ")", expected a module field or a module.`,
-	},
-
 	{
 		watCode: `(module)`,
 		errMsg:  "",
@@ -70,43 +61,12 @@ var watTests = []struct {
 		errMsg: "",
 	},
 
-	{
-		watCode: t_hello_wasi,
-		errMsg:  "",
-	},
 	{
 		watCode: tBuildWat(t_hello_wa),
 		errMsg:  "",
 	},
 }
 
-const t_hello_wasi = `
-(module $hello_wasi
-    ;; type iov struct { iov_base, iov_len int32 }
-    ;; func fd_write(id *iov, iovs_len int32, nwritten *int32) (written int32)
-    (import "wasi_unstable" "fd_write" (func $fd_write (param i32 i32 i32 i32) (result i32)))
-
-    (memory 1)(export "memory" (memory 0))
-
-    ;; 前 8 个字节保留给 iov 数组, 字符串从地址 8 开始
-    (data (i32.const 8) "hello world\n")
-
-    ;; _start 类似 main 函数, 自动执行
-    (func $main (export "_start")
-        (i32.store (i32.const 0) (i32.const 8))  ;; iov.iov_base - 字符串地址为 8
-        (i32.store (i32.const 4) (i32.const 12)) ;; iov.iov_len  - 字符串长度
-
-        (call $fd_write
-            (i32.const 1)  ;; 1 对应 stdout
-            (i32.const 0)  ;; *iovs - 前 8 个字节保留给 iov 数组
-            (i32.const 1)  ;; len(iovs) - 只有1个字符串
-            (i32.const 20) ;; nwritten - 指针, 里面是要写到数据长度
-        )
-        drop ;; 忽略返回值
-    )
-)
-`
-
 const t_hello_wa = `
 // 版权 @2019 凹语言 作者。保留所有权利。
 
diff --git a/internal/wat/parser/module_func_instruction.go b/internal/wat/parser/module_func_instruction.go
index b47489f9..ed0950f0 100644
--- a/internal/wat/parser/module_func_instruction.go
+++ b/internal/wat/parser/module_func_instruction.go
@@ -719,7 +719,7 @@ func (p *parser) parseIns_I32Load16S() (i ast.Ins_I32Load16S) {
 }
 func (p *parser) parseIns_I32Load16U() (i ast.Ins_I32Load16U) {
 	i.OpToken = ast.OpToken(p.tok)
-	p.acceptToken(token.INS_I32_LOAD16_S)
+	p.acceptToken(token.INS_I32_LOAD16_U)
 	if p.tok == token.OFFSET {
 		p.acceptToken(token.OFFSET)
 		p.acceptToken(token.ASSIGN)
diff --git a/internal/wat/parser/parser.go b/internal/wat/parser/parser.go
index 3776299a..1da61ccb 100644
--- a/internal/wat/parser/parser.go
+++ b/internal/wat/parser/parser.go
@@ -170,11 +170,16 @@ func (p *parser) parseInt32Lit() int32 {
 	p.acceptToken(token.INT)
 
 	// 需要支持 u32 和 -1 两种格式
-	n, err := strconv.ParseInt(lit, 10, 33)
+	n, err := strconv.ParseInt(lit, 10, 32)
 	if err != nil {
-		p.errorf(pos, "expect int, got %q, err = %v", lit, err)
+		if n, errx := strconv.ParseUint(lit, 10, 32); errx == nil {
+			return int32(uint32(n))
+		} else {
+			p.errorf(pos, "expect int, got %q, err = %v", lit, err)
+		}
+
 	}
-	return int32(uint32(n))
+	return int32(n)
 }
 func (p *parser) parseUint32Lit() uint32 {
 	pos, lit := p.pos, p.lit
@@ -190,7 +195,7 @@ func (p *parser) parseInt64Lit() int64 {
 	pos, lit := p.pos, p.lit
 	p.acceptToken(token.INT)
 
-	n, err := strconv.ParseUint(lit, 10, 64)
+	n, err := strconv.ParseInt(lit, 10, 64)
 	if err != nil {
 		p.errorf(pos, "expect int, got %q", lit)
 	}
diff --git a/waroot/src/src.go b/waroot/src/src.go
index 1ed81704..7ba76948 100644
--- a/waroot/src/src.go
+++ b/waroot/src/src.go
@@ -100,7 +100,7 @@ var stdPkgs = []string{
 	"apple",           // 测试已覆盖, wat2wasm ok
 	"archive/txtar",   // API 完整, wat2wasm ok
 	"bufio",           // API 完整, wat2wasm ok
-	"bytes",           // API 完整, wat2wasm failed
+	"bytes",           // API 完整, wat2wasm ok
 	"compress/snappy", // ?
 	"container/heap",  // ?
 	"container/list",  // ?
@@ -108,11 +108,11 @@ var stdPkgs = []string{
 	"crypto/md5",      // ?, 测试失败, Skip, wat2wasm ok
 	"errors",          // API 完整, 测试已覆盖, wat2wasm ok
 	"encoding",        // API 完整, wat2wasm ok
-	"encoding/base32", // ?, wat2wasm failed
-	"encoding/base64", // API 完整, wat2wasm failed
-	"encoding/binary", // API 部分, wat2wasm failed
+	"encoding/base32", // ?, wat2wasm ok
+	"encoding/base64", // API 完整, wat2wasm ok
+	"encoding/binary", // API 部分, wat2wasm ok
 	"encoding/hex",    // API 完整, wat2wasm ok
-	"encoding/pem",    // ?, wat2wasm failed
+	"encoding/pem",    // ?, wat2wasm ok
 	"encoding/qrcode", // ?
 	"debug",           // ?
 	"fmt",             // ?, wat2wasm ok
@@ -128,18 +128,18 @@ var stdPkgs = []string{
 	"js/canvas",       // ?
 	"js/p5",           // ?
 	"math",            // API 部分
-	"math/big",        // API 部分, wat2wasm failed
-	"math/bits",       // API 完整, wat2wasm failed
-	"math/gf256",      // ?, wat2wasm failed
+	"math/big",        // API 部分, wat2wasm ok
+	"math/bits",       // API 完整, wat2wasm ok
+	"math/gf256",      // ?, wat2wasm ok
 	"net",             // ?
 	"os",              // API 部分, wat2wasm ok
-	"reflect",         // ?, wat2wasm failed
+	"reflect",         // ?
 	"regexp",          // API 部分
 	"runtime",         //
-	"sort",            // API 完整, wat2wasm failed
-	"strconv",         // API 完整, wat2wasm failed
+	"sort",            // API 完整, wat2wasm ok
+	"strconv",         // API 完整, wat2wasm ok
 	"strings",         // API 完整, wat2wasm ok
-	"syscall",         // API 完整, wat2wasm failed
+	"syscall",         // API 完整
 	"syscall/js",      //
 	"syscall/wasi",    //
 	"syscall/unknown", //