diff --git a/src/testdir/test_assert.vim b/src/testdir/test_assert.vim
index 47dcc1f..04fde2d 100644
--- a/src/testdir/test_assert.vim
+++ b/src/testdir/test_assert.vim
@@ -254,35 +254,35 @@
   catch
     let exp = v:exception
   endtry
-  call assert_match("E856: assert_fails() second argument", exp)
+  call assert_match("E856: \"assert_fails()\" second argument", exp)
 
   try
     call assert_equal(1, assert_fails('xxx', ['1', '2', '3']))
   catch
     let exp = v:exception
   endtry
-  call assert_match("E856: assert_fails() second argument", exp)
+  call assert_match("E856: \"assert_fails()\" second argument", exp)
 
   try
     call assert_equal(1, assert_fails('xxx', #{one: 1}))
   catch
     let exp = v:exception
   endtry
-  call assert_match("E856: assert_fails() second argument", exp)
+  call assert_match("E856: \"assert_fails()\" second argument", exp)
 
   try
     call assert_equal(1, assert_fails('xxx', 'E492', '', 'burp'))
   catch
     let exp = v:exception
   endtry
-  call assert_match("E1115: assert_fails() fourth argument must be a number", exp)
+  call assert_match("E1115: \"assert_fails()\" fourth argument must be a number", exp)
 
   try
     call assert_equal(1, assert_fails('xxx', 'E492', '', 54, 123))
   catch
     let exp = v:exception
   endtry
-  call assert_match("E1116: assert_fails() fifth argument must be a string", exp)
+  call assert_match("E1116: \"assert_fails()\" fifth argument must be a string", exp)
 endfunc
 
 func Test_assert_fails_in_try_block()