diff --git a/internal/build/main_module.go b/internal/build/main_module.go
index 760177ce..8076bf61 100644
--- a/internal/build/main_module.go
+++ b/internal/build/main_module.go
@@ -22,7 +22,6 @@ package build
 import (
 	"go/token"
 	"go/types"
-	"runtime"
 
 	"github.com/goplus/llgo/internal/packages"
 	llvm "github.com/goplus/llvm"
@@ -32,13 +31,12 @@ import (
 
 func genMainModule(ctx *context, rtPkgPath string, pkg *packages.Package, needRuntime, needPyInit bool) Package {
 	prog := ctx.prog
-	mainPkg := prog.NewPackage("", pkg.PkgPath+".main")
+	mainPkg := prog.NewPackage("", pkg.ID+".main")
 
 	argcVar := mainPkg.NewVarEx("__llgo_argc", prog.Pointer(prog.Int32()))
 	argcVar.Init(prog.Zero(prog.Int32()))
 
-	charPtrType := prog.Pointer(prog.Byte())
-	argvValueType := prog.Pointer(charPtrType)
+	argvValueType := prog.Pointer(prog.CStr())
 	argvVar := mainPkg.NewVarEx("__llgo_argv", prog.Pointer(argvValueType))
 	argvVar.InitNil()
 
@@ -59,6 +57,7 @@ func genMainModule(ctx *context, rtPkgPath string, pkg *packages.Package, needRu
 	}
 
 	runtimeStub := defineWeakNoArgStub(mainPkg, "runtime.init")
+	// TODO(lijie): workaround for syscall patch
 	defineWeakNoArgStub(mainPkg, "syscall.init")
 
 	var pyInit llssa.Function
@@ -144,9 +143,8 @@ func emitStdioNobuf(b llssa.Builder, pkg llssa.Package, goarch string) {
 	stderr := declareExternalPtrGlobal(pkg, "stderr", streamType)
 	stdoutAlt := declareExternalPtrGlobal(pkg, "__stdout", streamType)
 	stderrAlt := declareExternalPtrGlobal(pkg, "__stderr", streamType)
-	sizeType := sizeTypeForArch(prog, goarch)
-	charPtrType := prog.Pointer(prog.Byte())
-	setvbuf := declareSetvbuf(pkg, streamPtrType, charPtrType, prog.Int32(), sizeType)
+	sizeType := prog.Uintptr()
+	setvbuf := declareSetvbuf(pkg, streamPtrType, prog.CStr(), prog.Int32(), sizeType)
 
 	stdoutSlot := b.AllocaT(streamPtrType)
 	b.Store(stdoutSlot, stdout)
@@ -166,7 +164,7 @@ func emitStdioNobuf(b llssa.Builder, pkg llssa.Package, goarch string) {
 
 	mode := prog.IntVal(2, prog.Int32())
 	zeroSize := prog.Zero(sizeType)
-	nullBuf := prog.Nil(charPtrType)
+	nullBuf := prog.Nil(prog.CStr())
 
 	b.Call(setvbuf.Expr, stdoutPtr, nullBuf, mode, zeroSize)
 	b.Call(setvbuf.Expr, stderrPtr, nullBuf, mode, zeroSize)
@@ -213,13 +211,3 @@ func newEntrySignature(argvType types.Type) *types.Signature {
 		[]types.Type{types.Typ[types.Int32]},
 	)
 }
-
-func sizeTypeForArch(prog llssa.Program, arch string) llssa.Type {
-	if arch == "" {
-		arch = runtime.GOARCH
-	}
-	if is32Bits(arch) {
-		return prog.Uint32()
-	}
-	return prog.Uint64()
-}