diff --git a/index.js b/index.js
index 3802df93..8a4f541b 100644
--- a/index.js
+++ b/index.js
@@ -5,6 +5,7 @@ const globby = require('globby');
 const isEqual = require('lodash.isequal');
 const multimatch = require('multimatch');
 const arrify = require('arrify');
+const slash = require('slash');
 const optionsManager = require('./options-manager');
 
 exports.lintText = (str, opts) => {
@@ -30,7 +31,7 @@ exports.lintText = (str, opts) => {
 	if (opts.filename) {
 		const filename = path.relative(opts.cwd, opts.filename);
 		const isIgnored = multimatch(filename, opts.ignores).length > 0;
-		const isGitIgnored = !optionsManager.getGitIgnoreFilter(opts)(opts.filename);
+		const isGitIgnored = !optionsManager.getGitIgnoreFilter(opts)(slash(opts.filename));
 
 		if (isIgnored || isGitIgnored) {
 			return {