diff --git a/autoload/ale/engine.vim b/autoload/ale/engine.vim
index 8916987..dd871c3 100644
--- a/autoload/ale/engine.vim
+++ b/autoload/ale/engine.vim
@@ -366,9 +366,6 @@ function! s:RemapItemTypes(type_map, loclist) abort
     endfor
 endfunction
 
-" Save the temporary directory so we can figure out if files are in it.
-let s:temp_dir = fnamemodify(tempname(), ':h')
-
 function! ale#engine#FixLocList(buffer, linter_name, loclist) abort
     let l:bufnr_map = {}
     let l:new_loclist = []
diff --git a/autoload/ale/path.vim b/autoload/ale/path.vim
index 16dabf2..91832b3 100644
--- a/autoload/ale/path.vim
+++ b/autoload/ale/path.vim
@@ -84,12 +84,12 @@ function! ale#path#IsAbsolute(filename) abort
     return a:filename[:0] is# '/' || a:filename[1:2] is# ':\'
 endfunction
 
-let s:temp_dir = fnamemodify(tempname(), ':h')
+let s:temp_dir = ale#path#Simplify(fnamemodify(tempname(), ':h'))
 
 " Given a filename, return 1 if the file represents some temporary file
 " created by Vim.
 function! ale#path#IsTempName(filename) abort
-    return a:filename[:len(s:temp_dir) - 1] is# s:temp_dir
+    return ale#path#Simplify(a:filename)[:len(s:temp_dir) - 1] is# s:temp_dir
 endfunction
 
 " Given a base directory, which must not have a trailing slash, and a
diff --git a/test/test_loclist_corrections.vader b/test/test_loclist_corrections.vader
index 6224d60..46c7e27 100644
--- a/test/test_loclist_corrections.vader
+++ b/test/test_loclist_corrections.vader
@@ -324,7 +324,7 @@ Execute(FixLocList should interpret temporary filenames as being the current buf
   \   'foobar',
   \   [
   \     {'text': 'a', 'lnum': 2, 'filename': b:temp_name},
-  \     {'text': 'a', 'lnum': 3, 'filename': b:temp_name},
+  \     {'text': 'a', 'lnum': 3, 'filename': substitute(b:temp_name, '\\', '/', 'g')},
   \   ],
   \ )