diff --git a/src/testdir/test_exists.vim b/src/testdir/test_exists.vim
index 9cdb3fb..404b15c 100644
--- a/src/testdir/test_exists.vim
+++ b/src/testdir/test_exists.vim
@@ -113,6 +113,13 @@
   " Internal command with a count
   call assert_equal(0, exists(':3buffer'))
 
+  " Valid internal command (full match)
+  call assert_equal(2, exists(':k'))
+  " Non-existing internal command (':k' with arg 'e')
+  call assert_equal(0, exists(':ke'))
+  " Valid internal command (partial match)
+  call assert_equal(1, exists(':kee'))
+
   " User defined command (full match)
   command! MyCmd :echo 'My command'
   call assert_equal(2, exists(':MyCmd'))