diff --git a/Libraries/Network/NetInfo.js b/Libraries/Network/NetInfo.js
index 2b17603ad..d4295754f 100644
--- a/Libraries/Network/NetInfo.js
+++ b/Libraries/Network/NetInfo.js
@@ -229,7 +229,7 @@ const NetInfo = {
     },
   },
 
-  isConnectionExpensive(callback: (metered: ?boolean, error: string) => void): void {
+  isConnectionExpensive(callback: (metered: ?boolean, error?: string) => void): void {
     if (Platform.OS === 'android') {
       RCTNetInfo.isConnectionMetered((_isMetered) => {
         callback(_isMetered);