diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index ff07916..6baba97 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -4,7 +4,7 @@
 source check.vim
 source term_util.vim
 source screendump.vim
-source vim9.vim
+import './vim9.vim' as v9
 
 " Must be done first, since the alternate buffer must be unset.
 func Test_00_bufexists()
@@ -174,7 +174,7 @@
 
   if has('float')
     call assert_equal(3, strwidth(1.2))
-    call CheckDefAndScriptFailure(['echo strwidth(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
+    call v9.CheckDefAndScriptFailure(['echo strwidth(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
   endif
 
   set ambiwidth&
@@ -241,7 +241,7 @@
   call assert_fails('call str2nr({->2})', 'E729:')
   if has('float')
     call assert_equal(1, str2nr(1.2))
-    call CheckDefAndScriptFailure(['echo str2nr(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
+    call v9.CheckDefAndScriptFailure(['echo str2nr(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
   endif
   call assert_fails('call str2nr(10, [])', 'E745:')
 endfunc
@@ -503,7 +503,7 @@
   call assert_fails('call simplify({})', 'E731:')
   if has('float')
     call assert_equal('1.2', simplify(1.2))
-    call CheckDefAndScriptFailure(['echo simplify(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
+    call v9.CheckDefAndScriptFailure(['echo simplify(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
   endif
 endfunc
 
@@ -2265,7 +2265,7 @@
       let Time = 'localtime'
       call Time()
   END
-  call CheckScriptFailure(lines, 'E1085:')
+  call v9.CheckScriptFailure(lines, 'E1085:')
 endfunc
 
 func Test_char2nr()
@@ -2800,7 +2800,7 @@
     vim9script
     var s:trim = (x) => " " .. x
   END
-  call CheckScriptFailure(lines, 'E704:')
+  call v9.CheckScriptFailure(lines, 'E704:')
 
   call assert_fails('call extend(g:, #{foo: { -> "foo" }})', 'E704:')
   let g:bar = 123