diff --git a/gitignore.js b/gitignore.js
index 982834c..9ecbc05 100644
--- a/gitignore.js
+++ b/gitignore.js
@@ -44,8 +44,20 @@ const reduceIgnore = files => {
 	}, gitIgnore());
 };
 
+const ensureAbsolutePathForCwd = (cwd, p) => {
+	if (path.isAbsolute(p)) {
+		if (p.startsWith(cwd)) {
+			return p;
+		}
+
+		throw new Error(`Path ${p} is not in cwd ${cwd}`);
+	}
+
+	return path.join(cwd, p);
+};
+
 const getIsIgnoredPredecate = (ignores, cwd) => {
-	return p => ignores.ignores(slash(path.relative(cwd, p)));
+	return p => ignores.ignores(slash(path.relative(cwd, ensureAbsolutePathForCwd(cwd, p))));
 };
 
 const getFile = (file, cwd) => {
diff --git a/package.json b/package.json
index b345ab4..570174f 100644
--- a/package.json
+++ b/package.json
@@ -61,7 +61,7 @@
 		"dir-glob": "^2.2.2",
 		"fast-glob": "^2.2.6",
 		"glob": "^7.1.3",
-		"ignore": "^4.0.3",
+		"ignore": "^5.1.1",
 		"pify": "^4.0.1",
 		"slash": "^2.0.0"
 	},