diff --git a/package.json b/package.json
index 0629f56..df789a9 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
-  "files": ["dist/**/*"],
+  "files": ["./time-ranges.pegjs", "./dist/**/*"],
   "scripts": {
     "test": "npm run build && node dist/test.js",
     "test:watch": "nodemon --watch tsconfig.json --watch index.ts --watch parser.ts --watch time-ranges.pegjs --exec \"npm run test\"",
diff --git a/parser.ts b/parser.ts
index d5b9518..f52c0d7 100644
--- a/parser.ts
+++ b/parser.ts
@@ -1,5 +1,7 @@
 import fs from "fs";
+import path from "path";
 import peg from "pegjs";
 
-const grammar = fs.readFileSync("./time-ranges.pegjs", "utf-8");
+const grammarPath = path.resolve(__dirname, "..", "time-ranges.pegjs");
+const grammar = fs.readFileSync(grammarPath, "utf-8");
 export const parser = peg.generate(grammar);