diff --git a/autoload/ale/fix.vim b/autoload/ale/fix.vim
index 48874a8a..a14638c7 100644
--- a/autoload/ale/fix.vim
+++ b/autoload/ale/fix.vim
@@ -202,10 +202,10 @@ function! s:RunFixer(options) abort
             \   ? call(l:Function, [l:buffer, a:options.output])
             \   : call(l:Function, [l:buffer, a:options.output, copy(l:input)])
         else
-            " Chained commands accept (buffer, [done, input])
+            " Chained commands accept (buffer, [input])
             let l:result = ale#util#FunctionArgCount(l:Function) == 1
             \   ? call(l:Function, [l:buffer])
-            \   : call(l:Function, [l:buffer, v:null, copy(l:input)])
+            \   : call(l:Function, [l:buffer, copy(l:input)])
         endif
 
         if type(l:result) is v:t_number && l:result == 0
diff --git a/autoload/ale/fixers/generic.vim b/autoload/ale/fixers/generic.vim
index 1d88553e..cb8865b4 100644
--- a/autoload/ale/fixers/generic.vim
+++ b/autoload/ale/fixers/generic.vim
@@ -1,7 +1,7 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Generic functions for fixing files with.
 
-function! ale#fixers#generic#RemoveTrailingBlankLines(buffer, done, lines) abort
+function! ale#fixers#generic#RemoveTrailingBlankLines(buffer, lines) abort
     let l:end_index = len(a:lines) - 1
 
     while l:end_index > 0 && empty(a:lines[l:end_index])
@@ -12,7 +12,7 @@ function! ale#fixers#generic#RemoveTrailingBlankLines(buffer, done, lines) abort
 endfunction
 
 " Remove all whitespaces at the end of lines
-function! ale#fixers#generic#TrimWhitespace(buffer, done, lines) abort
+function! ale#fixers#generic#TrimWhitespace(buffer, lines) abort
     let l:index = 0
     let l:lines_new = range(len(a:lines))
 
diff --git a/autoload/ale/fixers/generic_python.vim b/autoload/ale/fixers/generic_python.vim
index 9a929b96..d55a23c3 100644
--- a/autoload/ale/fixers/generic_python.vim
+++ b/autoload/ale/fixers/generic_python.vim
@@ -2,7 +2,7 @@
 " Description: Generic fixer functions for Python.
 
 " Add blank lines before control statements.
-function! ale#fixers#generic_python#AddLinesBeforeControlStatements(buffer, done, lines) abort
+function! ale#fixers#generic_python#AddLinesBeforeControlStatements(buffer, lines) abort
     let l:new_lines = []
     let l:last_indent_size = 0
     let l:last_line_is_blank = 0
@@ -41,7 +41,7 @@ endfunction
 
 " This function breaks up long lines so that autopep8 or other tools can
 " fix the badly-indented code which is produced as a result.
-function! ale#fixers#generic_python#BreakUpLongLines(buffer, done, lines) abort
+function! ale#fixers#generic_python#BreakUpLongLines(buffer, lines) abort
     " Default to a maximum line length of 79
     let l:max_line_length = 79
     let l:conf = ale#path#FindNearestFile(a:buffer, 'setup.cfg')
diff --git a/autoload/ale/fixers/help.vim b/autoload/ale/fixers/help.vim
index 9fb0717b..b20740fe 100644
--- a/autoload/ale/fixers/help.vim
+++ b/autoload/ale/fixers/help.vim
@@ -1,7 +1,7 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Generic fixer functions for Vim help documents.
 
-function! ale#fixers#help#AlignTags(buffer, done, lines) abort
+function! ale#fixers#help#AlignTags(buffer, lines) abort
     let l:new_lines = []
 
     for l:line in a:lines
diff --git a/doc/ale.txt b/doc/ale.txt
index 16f7262d..efba5e35 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -578,14 +578,10 @@ The values for `g:ale_fixers` can be a list of |String|, |Funcref|, or
 for a function set in the ALE fixer registry.
 
 Each function for fixing errors must accept either one argument `(buffer)` or
-three arguments `(buffer, done, lines)`, representing the buffer being fixed,
-a function to call with results, and the lines to fix. The functions must
-return either `0`, for changing nothing, a |List| for new lines to set, a
-|Dictionary| for describing a command to be run in the background, or `v:true`
-for indicating that results will be provided asynchronously via the `done`
-callback.
-
-NOTE: The `done` function has not been implemented yet.
+two arguments `(buffer, lines)`, representing the buffer being fixed and the
+lines to fix. The functions must return either `0`, for changing nothing, a
+|List| for new lines to set, or a |Dictionary| for describing a command to be
+run in the background.
 
 Functions receiving a variable number of arguments will not receive the second
 argument `lines`. Functions should name two arguments if the `lines` argument
diff --git a/test/fix/test_ale_fix.vader b/test/fix/test_ale_fix.vader
index 500eb71c..bf18345d 100644
--- a/test/fix/test_ale_fix.vader
+++ b/test/fix/test_ale_fix.vader
@@ -34,21 +34,21 @@ Before:
   call ale#test#SetFilename('test.txt')
   call ale#linter#PreventLoading('testft')
 
-  function AddCarets(buffer, done, lines) abort
+  function AddCarets(buffer, lines) abort
     " map() is applied to the original lines here.
     " This way, we can ensure that defensive copies are made.
     return map(a:lines, '''^'' . v:val')
   endfunction
 
-  function AddDollars(buffer, done, lines) abort
+  function AddDollars(buffer, lines) abort
     return map(a:lines, '''$'' . v:val')
   endfunction
 
-  function DoNothing(buffer, done, lines) abort
+  function DoNothing(buffer, lines) abort
     return 0
   endfunction
 
-  function CatLine(buffer, done, lines) abort
+  function CatLine(buffer, lines) abort
     return {'command': 'cat - <(echo d)'}
   endfunction
 
@@ -56,15 +56,15 @@ Before:
     return {'command': 'cat - <(echo d)'}
   endfunction
 
-  function ReplaceWithTempFile(buffer, done, lines) abort
+  function ReplaceWithTempFile(buffer, lines) abort
     return {'command': 'echo x > %t', 'read_temporary_file': 1}
   endfunction
 
-  function CatWithTempFile(buffer, done, lines) abort
+  function CatWithTempFile(buffer, lines) abort
     return {'command': 'cat %t <(echo d)'}
   endfunction
 
-  function RemoveLastLine(buffer, done, lines) abort
+  function RemoveLastLine(buffer, lines) abort
     return ['a', 'b']
   endfunction
 
@@ -127,11 +127,11 @@ Before:
   endfunction
 
   " echo will output a single blank line, and we should ingore it.
-  function! IgnoredEmptyOutput(buffer, done, output)
+  function! IgnoredEmptyOutput(buffer, output)
     return {'command': has('win32') ? 'echo(' : 'echo'}
   endfunction
 
-  function! EchoLineNoPipe(buffer, done, output)
+  function! EchoLineNoPipe(buffer, output)
     return {'command': 'echo new line', 'read_buffer': 0}
   endfunction
 
@@ -438,7 +438,7 @@ Execute(ALEFix should accept lambdas):
     " to make the test pass.
     call setline(1, ['a', 'b', 'c', 'd'])
   else
-    let g:ale_fixers.testft = [{buffer, done, lines -> lines + ['d']}]
+    let g:ale_fixers.testft = [{buffer, lines -> lines + ['d']}]
     ALEFix
     call ale#test#FlushJobs()
   endif
diff --git a/test/fixers/test_break_up_long_lines_python_fixer.vader b/test/fixers/test_break_up_long_lines_python_fixer.vader
index 847d3358..5fd991f0 100644
--- a/test/fixers/test_break_up_long_lines_python_fixer.vader
+++ b/test/fixers/test_break_up_long_lines_python_fixer.vader
@@ -16,7 +16,7 @@ Execute(Long lines with basic function calls should be broken up correctly):
   \   ' bar,',
   \   '))',
   \ ],
-  \ ale#fixers#generic_python#BreakUpLongLines(bufnr(''), v:null, [
+  \ ale#fixers#generic_python#BreakUpLongLines(bufnr(''), [
   \   'def foo():',
   \   '    some_variable = this_is_a_longer_function(first_argument, second_argument, third_with_function_call(foo, bar))',
   \ ])
@@ -33,7 +33,7 @@ Execute(Longer lines should be permitted if a configuration file allows it):
   \   ' a_third_long_word,',
   \   ')'
   \ ],
-  \ ale#fixers#generic_python#BreakUpLongLines(bufnr(''), v:null, [
+  \ ale#fixers#generic_python#BreakUpLongLines(bufnr(''), [
   \   'x = this_line_is_between_79_and_90_characters(first, second, third, fourth, fifth)',
   \   'y = this_line_is_longer_than_90_characters(much_longer_word, another_longer_word, a_third_long_word)',
   \ ])
diff --git a/test/fixers/test_trim_whitespace.vader b/test/fixers/test_trim_whitespace.vader
index 10070374..2ffbcb04 100644
--- a/test/fixers/test_trim_whitespace.vader
+++ b/test/fixers/test_trim_whitespace.vader
@@ -16,13 +16,13 @@ Execute(Should delete all whitespace at the end of different lines):
   \   ' bar,',
   \   '))',
   \ ],
-  \ ale#fixers#generic#TrimWhitespace(bufnr(''), v:null, [
-  \   'def foo():',
-  \   '    some_variable = this_is_a_longer_function(',
-  \   'first_argument,',
-  \   ' second_argument,',
-  \   ' third_with_function_call(',
-  \   'foo,',
-  \   ' bar,',
-  \   '))',
+  \ ale#fixers#generic#TrimWhitespace(bufnr(''), [
+  \   'def foo():',     
+  \   '    some_variable = this_is_a_longer_function(', 
+  \   'first_argument,',  
+  \   ' second_argument,',   
+  \   ' third_with_function_call(',      
+  \   'foo,', 
+  \   ' bar,',   
+  \   '))',              
   \ ])
diff --git a/test/test_no_linting_on_write_quit.vader b/test/test_no_linting_on_write_quit.vader
index 7ad08d08..bbd80d8f 100644
--- a/test/test_no_linting_on_write_quit.vader
+++ b/test/test_no_linting_on_write_quit.vader
@@ -23,7 +23,7 @@ Before:
     return [{'lnum': 1, 'col': 1, 'text': 'xxx'}]
   endfunction
 
-  function AddLine(buffer, done, lines) abort
+  function AddLine(buffer, lines) abort
     return a:lines + ['x']
   endfunction