diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 02b6585..a8506a8 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -570,6 +570,12 @@
   " invalid memory.
   call tolower("\xC0\x80\xC0")
   call tolower("123\xC0\x80\xC0")
+
+  " Test in latin1 encoding
+  let save_enc = &encoding
+  set encoding=latin1
+  call assert_equal("abc", tolower("ABC"))
+  let &encoding = save_enc
 endfunc
 
 func Test_toupper()
@@ -641,6 +647,12 @@
   " invalid memory.
   call toupper("\xC0\x80\xC0")
   call toupper("123\xC0\x80\xC0")
+
+  " Test in latin1 encoding
+  let save_enc = &encoding
+  set encoding=latin1
+  call assert_equal("ABC", toupper("abc"))
+  let &encoding = save_enc
 endfunc
 
 func Test_tr()
@@ -1160,6 +1172,10 @@
 
   call assert_equal(0, filewritable('doesnotexist'))
 
+  call mkdir('Xdir')
+  call assert_equal(2, filewritable('Xdir'))
+  call delete('Xdir', 'd')
+
   call delete('Xfilewritable')
   bw!
 endfunc