diff --git a/lib/fs/fs_windows.go b/lib/fs/fs_windows.go
index af2076afd..c28e1bce7 100644
--- a/lib/fs/fs_windows.go
+++ b/lib/fs/fs_windows.go
@@ -89,11 +89,7 @@ func mmap(fd int, length int) ([]byte, error) {
 		windows.CloseHandle(h)
 		return nil, os.NewSyscallError("MapViewOfFile", errno)
 	}
-	data := make([]byte, 0)
-	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&data))
-	hdr.Data = addr
-	hdr.Len = length
-	hdr.Cap = hdr.Len
+	data := unsafe.Slice(addr, length)
 
 	mmapByAddrLock.Lock()
 	mmapByAddr[addr] = h
@@ -105,8 +101,7 @@ func mmap(fd int, length int) ([]byte, error) {
 func mUnmap(data []byte) error {
 	// flush is not needed, since we perform only reading operation.
 	// In case of write, additional call FlushViewOfFile must be performed.
-	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
-	addr := header.Data
+	addr := uintptr(unsafe.Pointer(&data[0]))
 
 	mmapByAddrLock.Lock()
 	h, ok := mmapByAddr[addr]