diff --git a/drivers/mtd/tests/mtd_stresstest.c b/drivers/mtd/tests/mtd_stresstest.c
index 3729f679ae5d..2d7e6cffd6d4 100644
--- a/drivers/mtd/tests/mtd_stresstest.c
+++ b/drivers/mtd/tests/mtd_stresstest.c
@@ -282,8 +282,7 @@ static int __init mtd_stresstest_init(void)
 	}
 	for (i = 0; i < ebcnt; i++)
 		offsets[i] = mtd->erasesize;
-	for (i = 0; i < bufsize; i++)
-		writebuf[i] = random32();
+	prandom_bytes(writebuf, bufsize);
 
 	err = scan_for_bad_eraseblocks();
 	if (err)