diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index a54cede..47315ab 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -508,6 +508,11 @@
   END
   call v9.CheckLegacyAndVim9Success(lines)
 
+  if filereadable('/dev/random')
+    let b = readblob('/dev/random', 0, 10)
+    call assert_equal(10, len(b))
+  endif
+
   call assert_fails("call readblob('notexist')", 'E484:')
   " TODO: How do we test for the E485 error?