diff --git a/filesystem/fat32/testdata/fat32.go b/filesystem/fat32/testdata/fat32.go
index 01422e31..ec404e60 100644
--- a/filesystem/fat32/testdata/fat32.go
+++ b/filesystem/fat32/testdata/fat32.go
@@ -2,7 +2,7 @@ package main
 
 import (
 	"fmt"
-	"math/rand/v2"
+	"math/rand"
 	"os"
 	"strconv"
 
@@ -13,6 +13,7 @@ import (
 
 func main() {
 	filename := "test_file.img"
+	r := rand.New(rand.NewSource(37))
 	os.Remove(filename)
 	fs := mkfs(filename)
 	mkfile(fs, "/testfile")
@@ -23,7 +24,7 @@ func main() {
 		mkdir(fs, "/b/sub"+inc)
 		mkdir(fs, "/b/sub"+inc+"/blob/")
 		mkfile(fs, "/b/sub"+inc+"/blob/testfile1")
-		mkRandFile(fs, "/b/sub"+inc+"/blob/randFileSize")
+		mkRandFile(fs, "/b/sub"+inc+"/blob/randFileSize", r.Intn(73))
 		mkSmallFile(fs, "/b/sub"+inc+"/blob/testfile3")
 	}
 	mkSmallFile(fs, "/b/sub55/blob/testfile4")
@@ -70,14 +71,13 @@ func mkfile(fs filesystem.FileSystem, name string) {
 		panic(err)
 	}
 }
-func mkRandFile(fs filesystem.FileSystem, name string) {
+func mkRandFile(fs filesystem.FileSystem, name string, rSize int) {
 	rw, err := fs.OpenFile(name, os.O_CREATE|os.O_RDWR)
 	if err != nil {
 		panic(err)
 	}
 
-	randSize := rand.IntN(73)
-	size := randSize * 1024 * 1024
+	size := rSize * 1024 * 1024
 	smallFile := make([]byte, size, size)
 	_, err = rw.Write(smallFile)
 	if err != nil {