diff --git a/lib/modules/functions/HttpsError.js b/lib/modules/functions/HttpsError.js
new file mode 100644
index 00000000..6bded74a
--- /dev/null
+++ b/lib/modules/functions/HttpsError.js
@@ -0,0 +1,11 @@
+import type { FunctionsErrorCode } from './types.flow';
+
+export default class HttpsError extends Error {
+  +details: ?any;
+  +code: FunctionsErrorCode;
+  constructor(code: FunctionsErrorCode, message?: string, details?: any) {
+    super(message);
+    this.details = details;
+    this.code = code;
+  }
+}
diff --git a/lib/modules/functions/index.js b/lib/modules/functions/index.js
index f690d655..47ed054b 100644
--- a/lib/modules/functions/index.js
+++ b/lib/modules/functions/index.js
@@ -6,27 +6,18 @@ import ModuleBase from '../../utils/ModuleBase';
 import { isObject } from '../../utils';
 import { getNativeModule } from '../../utils/native';
 
+import type App from '../core/app';
+import HttpsError from './HttpsError';
+
 import type {
   HttpsCallable,
   HttpsErrorCode,
-  FunctionsErrorCode,
   HttpsCallablePromise,
 } from './types.flow';
-import type App from '../core/app';
 
 export const NAMESPACE = 'functions';
 export const MODULE_NAME = 'RNFirebaseFunctions';
 
-class HttpsError extends Error {
-  +details: ?any;
-  +code: FunctionsErrorCode;
-  constructor(code: string, message?: string, details?: any) {
-    super(message);
-    this.details = details;
-    this.code = statics.HttpsErrorCode[code] || statics.HttpsErrorCode.UNKNOWN;
-  }
-}
-
 export default class Functions extends ModuleBase {
   constructor(app: App) {
     super(app, {
@@ -62,7 +53,13 @@ export default class Functions extends ModuleBase {
   _errorOrResult(possibleError): HttpsCallablePromise {
     if (isObject(possibleError) && possibleError.__error) {
       const { code, message, details } = possibleError;
-      return Promise.reject(new HttpsError(code, message, details));
+      return Promise.reject(
+        new HttpsError(
+          statics.HttpsErrorCode[code] || statics.HttpsErrorCode.UNKNOWN,
+          message,
+          details
+        )
+      );
     }
 
     return Promise.resolve(possibleError);