diff --git a/package.json b/package.json
index 85263e8..56cbf6f 100644
--- a/package.json
+++ b/package.json
@@ -36,6 +36,7 @@
     "devDependencies": {
         "@types/node": "*",
         "del-cli": "*",
+        "gaxios": "*",
         "np": "*",
         "ts-node": "*",
         "tslib": "*",
diff --git a/src/index.ts b/src/index.ts
index 5190576..9ab6d81 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,6 @@
 import { google } from 'googleapis';
 
-import { GSheetOptions, RowArray, RowObject } from './types';
+import { GSheetOptions, RowArray, RowObject, GoogleSheetsAppendResponse } from './types';
 
 import { noChange, trim, gSheetDate, gSheetDateTime } from './util';
 
@@ -106,7 +106,7 @@ const gsheet = ({
         timer.unref();
     }
 
-    const append = async (arg: RowArray | RowObject) => {
+    const append = async (arg: RowArray | RowObject): GoogleSheetsAppendResponse => {
         let row: RowArray | undefined;
         if (Array.isArray(arg)) {
             row = arg;
diff --git a/src/types.ts b/src/types.ts
index bb3123d..b4f56fd 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,3 +1,5 @@
+import { sheets_v4 } from 'googleapis';
+import { GaxiosResponse } from 'gaxios';
 import { noChange, trim } from "./util";
 
 export type InputTypes = boolean | string | number | null;
@@ -24,3 +26,5 @@ export interface GSheetOptions {
     keyTransform?: typeof noChange;
     sanitize?: typeof trim;
 }
+
+export type GoogleSheetsAppendResponse = Promise<GaxiosResponse<sheets_v4.Schema$AppendValuesResponse>>;
\ No newline at end of file