diff --git a/internal/vfs/func.go b/internal/util/func.go
similarity index 68%
rename from internal/vfs/func.go
rename to internal/util/func.go
index cd56a90..0776721 100644
--- a/internal/vfs/func.go
+++ b/internal/util/func.go
@@ -1,4 +1,4 @@
-package vfs
+package util
 
 import (
 	"context"
@@ -7,7 +7,10 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
-func registerFunc1[T0, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0) TR) {
+type i32 interface{ ~int32 | ~uint32 }
+type i64 interface{ ~int64 | ~uint64 }
+
+func RegisterFuncII[TR, T0 i32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
@@ -17,7 +20,7 @@ func registerFunc1[T0, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn
 		Export(name)
 }
 
-func registerFunc2[T0, T1, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1) TR) {
+func RegisterFuncIII[TR, T0, T1 i32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
@@ -27,7 +30,7 @@ func registerFunc2[T0, T1, TR ~uint32](mod wazero.HostModuleBuilder, name string
 		Export(name)
 }
 
-func registerFunc3[T0, T1, T2, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2) TR) {
+func RegisterFuncIIII[TR, T0, T1, T2 i32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
@@ -37,7 +40,7 @@ func registerFunc3[T0, T1, T2, TR ~uint32](mod wazero.HostModuleBuilder, name st
 		Export(name)
 }
 
-func registerFunc4[T0, T1, T2, T3, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3) TR) {
+func RegisterFuncIIIII[TR, T0, T1, T2, T3 i32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
@@ -47,7 +50,7 @@ func registerFunc4[T0, T1, T2, T3, TR ~uint32](mod wazero.HostModuleBuilder, nam
 		Export(name)
 }
 
-func registerFunc5[T0, T1, T2, T3, T4, TR ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3, _ T4) TR) {
+func RegisterFuncIIIIII[TR, T0, T1, T2, T3, T4 i32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3, _ T4) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
@@ -57,21 +60,21 @@ func registerFunc5[T0, T1, T2, T3, T4, TR ~uint32](mod wazero.HostModuleBuilder,
 		Export(name)
 }
 
-func registerFuncRW(mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _, _, _ uint32, _ int64) _ErrorCode) {
+func RegisterFuncIIIIJ[TR, T0, T1, T2 i32, T3 i64](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
-				stack[0] = uint64(fn(ctx, mod, uint32(stack[0]), uint32(stack[1]), uint32(stack[2]), int64(stack[3])))
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1]), T2(stack[2]), T3(stack[3])))
 			}),
 			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI64}, []api.ValueType{api.ValueTypeI32}).
 		Export(name)
 }
 
-func registerFuncT(mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ uint32, _ int64) _ErrorCode) {
+func RegisterFuncIIJ[TR, T0 i32, T1 i64](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1) TR) {
 	mod.NewFunctionBuilder().
 		WithGoModuleFunction(api.GoModuleFunc(
 			func(ctx context.Context, mod api.Module, stack []uint64) {
-				stack[0] = uint64(fn(ctx, mod, uint32(stack[0]), int64(stack[1])))
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1])))
 			}),
 			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI64}, []api.ValueType{api.ValueTypeI32}).
 		Export(name)
diff --git a/internal/vfs/tests/mptest/mptest_test.go b/internal/vfs/tests/mptest/mptest_test.go
index bfe0078..ab652cf 100644
--- a/internal/vfs/tests/mptest/mptest_test.go
+++ b/internal/vfs/tests/mptest/mptest_test.go
@@ -40,7 +40,8 @@ func init() {
 
 	rt = wazero.NewRuntime(ctx)
 	wasi_snapshot_preview1.MustInstantiate(ctx, rt)
-	env := vfs.NewEnvModuleBuilder(rt)
+
+	env := vfs.Export(rt.NewHostModuleBuilder("env"))
 	env.NewFunctionBuilder().WithFunc(system).Export("system")
 	_, err := env.Instantiate(ctx)
 	if err != nil {
diff --git a/internal/vfs/tests/speedtest1/speedtest1_test.go b/internal/vfs/tests/speedtest1/speedtest1_test.go
index 911e770..2e9c2b7 100644
--- a/internal/vfs/tests/speedtest1/speedtest1_test.go
+++ b/internal/vfs/tests/speedtest1/speedtest1_test.go
@@ -35,7 +35,7 @@ func init() {
 
 	rt = wazero.NewRuntime(ctx)
 	wasi_snapshot_preview1.MustInstantiate(ctx, rt)
-	env := vfs.NewEnvModuleBuilder(rt)
+	env := vfs.Export(rt.NewHostModuleBuilder("env"))
 	_, err := env.Instantiate(ctx)
 	if err != nil {
 		panic(err)
diff --git a/internal/vfs/vfs.go b/internal/vfs/vfs.go
index fd641f2..9e7d742 100644
--- a/internal/vfs/vfs.go
+++ b/internal/vfs/vfs.go
@@ -17,37 +17,28 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
-func Instantiate(ctx context.Context, r wazero.Runtime) {
-	env := NewEnvModuleBuilder(r)
-	_, err := env.Instantiate(ctx)
-	if err != nil {
-		panic(err)
-	}
-}
-
-func NewEnvModuleBuilder(r wazero.Runtime) wazero.HostModuleBuilder {
-	env := r.NewHostModuleBuilder("env")
-	registerFuncT(env, "os_localtime", vfsLocaltime)
-	registerFunc3(env, "os_randomness", vfsRandomness)
-	registerFunc2(env, "os_sleep", vfsSleep)
-	registerFunc2(env, "os_current_time", vfsCurrentTime)
-	registerFunc2(env, "os_current_time_64", vfsCurrentTime64)
-	registerFunc4(env, "os_full_pathname", vfsFullPathname)
-	registerFunc3(env, "os_delete", vfsDelete)
-	registerFunc4(env, "os_access", vfsAccess)
-	registerFunc5(env, "os_open", vfsOpen)
-	registerFunc1(env, "os_close", vfsClose)
-	registerFuncRW(env, "os_read", vfsRead)
-	registerFuncRW(env, "os_write", vfsWrite)
-	registerFuncT(env, "os_truncate", vfsTruncate)
-	registerFunc2(env, "os_sync", vfsSync)
-	registerFunc2(env, "os_file_size", vfsFileSize)
-	registerFunc3(env, "os_file_control", vfsFileControl)
-	registerFunc1(env, "os_sector_size", vfsSectorSize)
-	registerFunc1(env, "os_device_characteristics", vfsDeviceCharacteristics)
-	registerFunc2(env, "os_lock", vfsLock)
-	registerFunc2(env, "os_unlock", vfsUnlock)
-	registerFunc2(env, "os_check_reserved_lock", vfsCheckReservedLock)
+func Export(env wazero.HostModuleBuilder) wazero.HostModuleBuilder {
+	util.RegisterFuncIIJ(env, "os_localtime", vfsLocaltime)
+	util.RegisterFuncIIII(env, "os_randomness", vfsRandomness)
+	util.RegisterFuncIII(env, "os_sleep", vfsSleep)
+	util.RegisterFuncIII(env, "os_current_time", vfsCurrentTime)
+	util.RegisterFuncIII(env, "os_current_time_64", vfsCurrentTime64)
+	util.RegisterFuncIIIII(env, "os_full_pathname", vfsFullPathname)
+	util.RegisterFuncIIII(env, "os_delete", vfsDelete)
+	util.RegisterFuncIIIII(env, "os_access", vfsAccess)
+	util.RegisterFuncIIIIII(env, "os_open", vfsOpen)
+	util.RegisterFuncII(env, "os_close", vfsClose)
+	util.RegisterFuncIIIIJ(env, "os_read", vfsRead)
+	util.RegisterFuncIIIIJ(env, "os_write", vfsWrite)
+	util.RegisterFuncIIJ(env, "os_truncate", vfsTruncate)
+	util.RegisterFuncIII(env, "os_sync", vfsSync)
+	util.RegisterFuncIII(env, "os_file_size", vfsFileSize)
+	util.RegisterFuncIIII(env, "os_file_control", vfsFileControl)
+	util.RegisterFuncII(env, "os_sector_size", vfsSectorSize)
+	util.RegisterFuncII(env, "os_device_characteristics", vfsDeviceCharacteristics)
+	util.RegisterFuncIII(env, "os_lock", vfsLock)
+	util.RegisterFuncIII(env, "os_unlock", vfsUnlock)
+	util.RegisterFuncIII(env, "os_check_reserved_lock", vfsCheckReservedLock)
 	return env
 }
 
diff --git a/module.go b/module.go
index e5e1335..85e04d4 100644
--- a/module.go
+++ b/module.go
@@ -52,7 +52,12 @@ func instantiateModule() (*module, error) {
 func compileModule() {
 	ctx := context.Background()
 	sqlite3.runtime = wazero.NewRuntime(ctx)
-	vfs.Instantiate(ctx, sqlite3.runtime)
+
+	env := vfs.Export(sqlite3.runtime.NewHostModuleBuilder("env"))
+	_, sqlite3.err = env.Instantiate(ctx)
+	if sqlite3.err != nil {
+		return
+	}
 
 	bin := Binary
 	if bin == nil && Path != "" {