diff --git a/c/lua/_demo/dump/load/load.go b/c/lua/_demo/dump/load/load.go
index 9e2cf242..32d9cd61 100644
--- a/c/lua/_demo/dump/load/load.go
+++ b/c/lua/_demo/dump/load/load.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"unsafe"
 
 	"github.com/goplus/llgo/c"
@@ -8,11 +9,26 @@ import (
 )
 
 func reader(L *lua.State, data c.Pointer, size *c.Ulong) *c.Char {
-	buffer := make([]c.Char, 4096)
-	*size = c.Ulong(c.Fread(c.Pointer(unsafe.SliceData(buffer)), uintptr(1), uintptr(unsafe.Sizeof(buffer)), data))
-	if *size > 0 {
-		return &buffer[0]
+	file := (*os.File)(data)
+
+	fileInfo, err := file.Stat()
+	if err != nil {
+		return nil
 	}
+	fileSize := fileInfo.Size()
+
+	buffer := make([]byte, fileSize)
+	bytesRead, err := file.Read(buffer)
+	if err != nil {
+		return nil
+	}
+
+	*size = c.Ulong(bytesRead)
+
+	if bytesRead > 0 {
+		return (*c.Char)(unsafe.Pointer(unsafe.SliceData(buffer)))
+	}
+
 	return nil
 }
 
@@ -21,12 +37,14 @@ func main() {
 	defer L.Close()
 	L.Openlibs()
 
-	file := c.Fopen(c.Str("../llgofunc.luac"), c.Str("rb"))
-	if file == nil {
-		c.Printf(c.Str("Failed to open file for writing\n"))
+	file, err := os.Open("../llgofunc.luac")
+	if err != nil {
+		c.Printf(c.Str("Failed to open file for reading\n"))
+		return
 	}
+	defer file.Close()
 
-	if L.Load(reader, file, c.Str("greet"), nil) != lua.OK {
+	if L.Load(reader, c.Pointer(file), c.Str("greet"), nil) != lua.OK {
 		c.Printf(c.Str("Failed to dump Lua function\n"))
 	}
 
@@ -42,3 +60,9 @@ func main() {
 		c.Printf(c.Str("Result: %s\n"), L.Tostring(-1))
 	}
 }
+
+/* Expected output:
+Stack size before call: 1
+Top element type after call: function
+Result: Hello, World!
+*/
diff --git a/c/lua/_demo/dump/save/save.go b/c/lua/_demo/dump/save/save.go
index 9e8edd74..e94cc2e5 100644
--- a/c/lua/_demo/dump/save/save.go
+++ b/c/lua/_demo/dump/save/save.go
@@ -1,15 +1,23 @@
 package main
 
 import (
+	"os"
+	"unsafe"
+
 	"github.com/goplus/llgo/c"
 	"github.com/goplus/llgo/c/lua"
 )
 
 func writer(L *lua.State, p c.Pointer, sz c.Ulong, ud c.Pointer) c.Int {
-	if c.Fwrite(p, uintptr(sz), 1, ud) == 1 {
-		return lua.OK
+	file := (*os.File)(ud)
+	data := unsafe.Slice((*byte)(p), sz)
+
+	n, err := file.Write(data)
+	if err != nil || n != int(sz) {
+		return 1
 	}
-	return 1
+
+	return lua.OK
 }
 
 func main() {
@@ -19,7 +27,7 @@ func main() {
 
 	if res := L.Loadstring(c.Str(`
 	function greet(name)
-	    return 'Hello, ' .. name .. '!'
+		return 'Hello, ' .. name .. '!'
 	end
 	return greet
 	`)); res != lua.OK {
@@ -34,19 +42,15 @@ func main() {
 		c.Printf(c.Str("Expected a function, but got %s"), L.Typename(L.Type(-1)))
 	}
 
-	file := c.Fopen(c.Str("../llgofunc.luac"), c.Str("wb"))
-	if file == nil {
+	file, err := os.Create("../llgofunc.luac")
+	if err != nil {
 		c.Printf(c.Str("Failed to open file for writing\n"))
+		return
 	}
+	defer file.Close()
 
-	if L.Dump(writer, file, 0) != lua.OK {
+	if L.Dump(writer, c.Pointer(file), 0) != lua.OK {
 		c.Printf(c.Str("Failed to dump Lua function\n"))
 	}
 
 }
-
-/* Expected output:
-Stack size before call: 1
-Top element type after call: function
-Result: Hello, World!
-*/