diff --git a/package.json b/package.json
index 0a283a0d5..9e9e23cd7 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
   "scripts": {
     "lint": "eslint .",
     "docs": "rm docs -rf && typedoc --gitRevision master --out docs src && cp -r website/. docs/",
+    "check": "npm run lint && npm test && npm run docs && git checkout origin/master docs",
     "unit": "mocha \"test/unit/**/*.ts\"",
     "integration": "mocha \"test/integration/**/*.ts\"",
     "e2e": "npm run build && mocha \"test/e2e/**/*.ts\"",
diff --git a/src/liquid.ts b/src/liquid.ts
index 5277a3602..f74347f75 100644
--- a/src/liquid.ts
+++ b/src/liquid.ts
@@ -34,8 +34,8 @@ export class Liquid {
     this.filters = new FilterMap(this.options.strictFilters)
     this.tags = new TagMap()
 
-    forOwn(builtinTags, (conf, name) => this.registerTag(snakeCase(name), conf))
-    forOwn(builtinFilters, (handler, name) => this.registerFilter(snakeCase(name), handler))
+    forOwn(builtinTags, (conf: TagImplOptions, name: string) => this.registerTag(snakeCase(name), conf))
+    forOwn(builtinFilters, (handler: FilterImplOptions, name: string) => this.registerFilter(snakeCase(name), handler))
   }
   public parse (html: string, filepath?: string): Template[] {
     const tokenizer = new Tokenizer(html, filepath)