diff --git a/file_system.go b/file_system.go
index 761a120..3c72610 100644
--- a/file_system.go
+++ b/file_system.go
@@ -298,7 +298,7 @@ type ReadDirRequest struct {
 
 	// The maximum number of bytes to return in ReadDirResponse.Data. A smaller
 	// number is acceptable.
-	Size uint64
+	Size int
 }
 
 type ReadDirResponse struct {
diff --git a/samples/hello_fs.go b/samples/hello_fs.go
index ad804d5..e6ad10a 100644
--- a/samples/hello_fs.go
+++ b/samples/hello_fs.go
@@ -69,7 +69,7 @@ func (fs *HelloFS) ReadDir(
 	// Resume at the specified offset into the array.
 	for _, e := range entries {
 		resp.Data = fuseutil.AppendDirent(resp.Data, e)
-		if uint64(len(resp.Data)) > req.Size {
+		if len(resp.Data) > req.Size {
 			resp.Data = resp.Data[:req.Size]
 			break
 		}