diff --git a/src/testdir/test_vartabs.vim b/src/testdir/test_vartabs.vim
index 3b8a9ce..156233d 100644
--- a/src/testdir/test_vartabs.vim
+++ b/src/testdir/test_vartabs.vim
@@ -146,6 +146,16 @@
   bwipeout!
 endfunc
 
+func Test_retab_invalid_arg()
+  new
+  call setline(1, "\ttext")
+  retab 0
+  call assert_fails("retab -8", 'E487: Argument must be positive')
+  call assert_fails("retab 10000", 'E475:')
+  call assert_fails("retab 720575940379279360", 'E475:')
+  bwipe!
+endfunc
+
 func Test_vartabs_breakindent()
   CheckOption breakindent
   new