diff --git a/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.h b/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.h
index 3dd8b2ae02..490b1d70b7 100644
--- a/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.h
+++ b/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.h
@@ -7,7 +7,7 @@
 #error "This file must be compiled with ARC enabled"
 #endif
 
-typedef void (^_DidFinish)(void *, NSURLSession *session,
+typedef void (^_DidFinish)(void *closure, NSURLSession *session,
                            NSURLSessionDownloadTask *downloadTask,
                            NSURL *location);
 typedef void (^_DidFinishWithLock)(NSCondition *lock, NSURLSession *session,
diff --git a/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.m b/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.m
index 4f17a3415e..bad263c96c 100644
--- a/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.m
+++ b/pkgs/cupertino_http/darwin/cupertino_http/Sources/cupertino_http/utils.m
@@ -1,7 +1,7 @@
 #import "utils.h"
 
 _DidFinish adaptFinishWithLock(_DidFinishWithLock block) {
-  return ^void(void *, NSURLSession *session,
+  return ^void(void *closure, NSURLSession *session,
                NSURLSessionDownloadTask *downloadTask, NSURL *location) {
     NSCondition *lock = [[NSCondition alloc] init];
     [lock lock];