diff --git a/src/liquid.ts b/src/liquid.ts
index 46b463b0c..33d0bc4d6 100644
--- a/src/liquid.ts
+++ b/src/liquid.ts
@@ -71,10 +71,10 @@ export class Liquid {
     return this.parser.parseFile(file, sync, LookupType.Layouts, currentFile)
   }
   public async parseFile (file: string): Promise<Template[]> {
-    return toPromise(this.parser.parseFile(file, false))
+    return toPromise<Template[]>(this.parser.parseFile(file, false))
   }
   public parseFileSync (file: string): Template[] {
-    return toValue(this.parser.parseFile(file, true))
+    return toValue<Template[]>(this.parser.parseFile(file, true))
   }
   public async renderFile (file: string, ctx?: object) {
     const templates = await this.parseFile(file)
diff --git a/src/parser/parser.ts b/src/parser/parser.ts
index 919b02783..4d0757ef4 100644
--- a/src/parser/parser.ts
+++ b/src/parser/parser.ts
@@ -14,7 +14,7 @@ import { FS } from '../fs/fs'
 import { toThenable, Thenable } from '../util/async'
 
 export default class Parser {
-  public parseFile: (file: string, sync?: boolean, type?: LookupType, currentFile?: string) => Iterator<Template[]>
+  public parseFile: (file: string, sync?: boolean, type?: LookupType, currentFile?: string) => IterableIterator<any>
 
   private liquid: Liquid
   private fs: FS
diff --git a/src/util/async.ts b/src/util/async.ts
index 86afbf878..f61d5d368 100644
--- a/src/util/async.ts
+++ b/src/util/async.ts
@@ -37,7 +37,7 @@ function isAsyncIterator (val: any): val is IterableIterator<any> {
 type Task<T> = Thenable<T>
 
 // convert an async iterator to a thenable (Promise compatible)
-export function toThenable<T> (val: IterableIterator<T> | Thenable<T> | any): Thenable<T> {
+export function toThenable<T> (val: IterableIterator<any> | Thenable<T> | any): Thenable<T> {
   if (isThenable(val)) return val
   if (isAsyncIterator(val)) return reduce()
   return createResolvedThenable(val)
@@ -64,12 +64,12 @@ export function toThenable<T> (val: IterableIterator<T> | Thenable<T> | any): Th
   }
 }
 
-export function toPromise<T> (val: IterableIterator<T> | Thenable<T> | T): Promise<T> {
+export function toPromise<T> (val: IterableIterator<any> | Thenable<T> | T): Promise<T> {
   return Promise.resolve(toThenable(val))
 }
 
 // get the value of async iterator in synchronous manner
-export function toValue<T> (val: IterableIterator<T> | Thenable<T> | T): T {
+export function toValue<T> (val: IterableIterator<any> | Thenable<T> | T): T {
   let ret: T
   toThenable(val)
     .then((x: any) => {