diff --git a/pkgs/ffigen/lib/src/code_generator.dart b/pkgs/ffigen/lib/src/code_generator.dart
index caad4143f..0197d5c04 100644
--- a/pkgs/ffigen/lib/src/code_generator.dart
+++ b/pkgs/ffigen/lib/src/code_generator.dart
@@ -11,7 +11,6 @@ export 'code_generator/constant.dart';
 export 'code_generator/enum_class.dart';
 export 'code_generator/func.dart';
 export 'code_generator/func_type.dart';
-export 'code_generator/future_type.dart';
 export 'code_generator/global.dart';
 export 'code_generator/handle.dart';
 export 'code_generator/imports.dart';
diff --git a/pkgs/ffigen/lib/src/code_generator/future_type.dart b/pkgs/ffigen/lib/src/code_generator/future_type.dart
deleted file mode 100644
index f5ef4da8d..000000000
--- a/pkgs/ffigen/lib/src/code_generator/future_type.dart
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import '../code_generator.dart';
-import '../visitor/ast.dart';
-
-import 'writer.dart';
-
-/// Represents a FutureOr<T>.
-class FutureOrType extends Type {
-  final Type child;
-
-  FutureOrType(this.child);
-
-  @override
-  String getCType(Writer w) => 'FutureOr<${child.getCType(w)}>';
-
-  @override
-  String getFfiDartType(Writer w) => 'FutureOr<${child.getFfiDartType(w)}>';
-
-  @override
-  String getDartType(Writer w) => 'FutureOr<${child.getDartType(w)}>';
-
-  @override
-  bool get sameFfiDartAndCType => child.sameFfiDartAndCType;
-
-  @override
-  String toString() => 'FutureOr<$child>';
-
-  @override
-  String cacheKey() => 'FutureOr<${child.cacheKey()}>';
-
-  @override
-  void visitChildren(Visitor visitor) {
-    super.visitChildren(visitor);
-    visitor.visit(child);
-  }
-
-  @override
-  bool isSupertypeOf(Type other) {
-    other = other.typealiasType;
-    if (other is FutureOrType) {
-      return child.isSupertypeOf(other.child);
-    }
-    return false;
-  }
-}
diff --git a/pkgs/ffigen/lib/src/code_generator/objc_block.dart b/pkgs/ffigen/lib/src/code_generator/objc_block.dart
index b015a305b..494dff038 100644
--- a/pkgs/ffigen/lib/src/code_generator/objc_block.dart
+++ b/pkgs/ffigen/lib/src/code_generator/objc_block.dart
@@ -134,6 +134,8 @@ class ObjCBlock extends BindingType {
         w.topLevelUniqueNamer.makeUnique('_${name}_blockingTrampoline');
     final blockingCallable =
         w.topLevelUniqueNamer.makeUnique('_${name}_blockingCallable');
+    final blockingListenerCallable =
+        w.topLevelUniqueNamer.makeUnique('_${name}_blockingListenerCallable');
     final callExtension =
         w.topLevelUniqueNamer.makeUnique('${name}_CallExtension');
 
@@ -180,14 +182,16 @@ $returnFfiDartType $listenerTrampoline(
 }
 ${func.trampNatCallType} $listenerCallable = ${func.trampNatCallType}.listener(
     $listenerTrampoline $exceptionalReturn)..keepIsolateAlive = false;
-Future<$returnFfiDartType> $blockingTrampoline(
-    $blockCType block, ${blockingFunc.paramsFfiDartType}) async {
-  await ($getBlockClosure(block) as ${func.asyncFfiDartType})(
-      ${func.paramsNameOnly});
+$returnFfiDartType $blockingTrampoline(
+    $blockCType block, ${blockingFunc.paramsFfiDartType}) {
+  ($getBlockClosure(block) as ${func.ffiDartType})(${func.paramsNameOnly});
   $signalWaiterFn(waiter);
   $releaseFn(block.cast());
 }
 ${blockingFunc.trampNatCallType} $blockingCallable =
+    ${blockingFunc.trampNatCallType}.isolateLocal(
+        $blockingTrampoline $exceptionalReturn)..keepIsolateAlive = false;
+${blockingFunc.trampNatCallType} $blockingListenerCallable =
     ${blockingFunc.trampNatCallType}.listener(
         $blockingTrampoline $exceptionalReturn)..keepIsolateAlive = false;
 ''');
@@ -282,8 +286,12 @@ abstract final class $name {
       ${func.dartType} fn, {Duration timeout = const Duration(seconds: 1)}) {
     final raw = $newClosureBlock(
         $blockingCallable.nativeFunction.cast(), $listenerConvFn);
-    final wrapper = $wrapBlockingBlockFn($wrapBlockingFn, raw, timeout);
+    final rawListener = $newClosureBlock(
+        $blockingListenerCallable.nativeFunction.cast(), $listenerConvFn);
+    final wrapper = $wrapBlockingBlockFn(
+        $wrapBlockingFn, raw, rawListener, timeout);
     $releaseFn(raw.cast());
+    $releaseFn(rawListener.cast());
     return $blockType(wrapper, retain: false, release: true);
   }
 ''');
@@ -334,7 +342,8 @@ ref.pointer.ref.invoke.cast<${func.trampNatFnCType}>()
     }
     final waiterParam = Parameter(
         name: 'waiter', type: PointerType(voidType), objCConsumed: false);
-    final blockingRetains = [waiterParam.name, ...retains];
+    final blockingRetains = ['nil', ...retains];
+    final blockingListenerRetains = [waiterParam.name, ...retains];
 
     final argStr = argsReceived.join(', ');
     final blockingArgStr = [
@@ -364,13 +373,20 @@ $listenerName $listenerWrapper($listenerName block) NS_RETURNS_RETAINED {
 typedef ${returnType.getNativeType()} (^$blockingName)($blockingArgStr);
 __attribute__((visibility("default"))) __attribute__((used))
 $listenerName $blockingWrapper(
-    $blockingName block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    $blockingName block, $blockingName listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void($argStr) {
-    void* waiter = newWaiter();
-    ${generateRetain('block')};
-    block(${blockingRetains.join(', ')});
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      ${generateRetain('block')};
+      block(${blockingRetains.join(', ')});
+    } else {
+      void* waiter = newWaiter();
+      ${generateRetain('listenerBlock')};
+      listenerBlock(${blockingListenerRetains.join(', ')});
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }
 ''');
@@ -456,7 +472,6 @@ class _FnHelper {
   late final String natFnPtrCType;
   late final String dartType;
   late final String ffiDartType;
-  late final String asyncFfiDartType;
   late final String trampCType;
   late final String trampFfiDartType;
   late final String trampNatCallType;
@@ -473,10 +488,6 @@ class _FnHelper {
     dartType = fnType.getDartType(w, writeArgumentNames: false);
     ffiDartType = fnType.getFfiDartType(w, writeArgumentNames: false);
 
-    final asyncFnType =
-        FunctionType(returnType: FutureOrType(returnType), parameters: params);
-    asyncFfiDartType = asyncFnType.getFfiDartType(w, writeArgumentNames: false);
-
     final trampFnType = FunctionType(
       returnType: returnType,
       parameters: [
diff --git a/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart b/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart
index 03adb25d9..50b01f395 100644
--- a/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart
+++ b/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart
@@ -229,6 +229,10 @@ class ObjCBuiltInFunctions {
               type: PointerType(objCBlockType),
               objCConsumed: false),
           if (blocking) ...[
+            Parameter(
+                name: 'listnerBlock',
+                type: PointerType(objCBlockType),
+                objCConsumed: false),
             Parameter(
                 name: 'timeoutSeconds', type: doubleType, objCConsumed: false),
             Parameter(
diff --git a/pkgs/ffigen/lib/src/code_generator/writer.dart b/pkgs/ffigen/lib/src/code_generator/writer.dart
index 7325d99ac..8e2bb9bc0 100644
--- a/pkgs/ffigen/lib/src/code_generator/writer.dart
+++ b/pkgs/ffigen/lib/src/code_generator/writer.dart
@@ -420,6 +420,7 @@ class Writer {
     final s = StringBuffer();
     s.write('''
 #include <stdint.h>
+#import <Foundation/Foundation.h>
 ''');
 
     for (final entryPoint in nativeEntryPoints) {
diff --git a/pkgs/ffigen/test/native_objc_test/block_test.dart b/pkgs/ffigen/test/native_objc_test/block_test.dart
index 450944b35..1d34f0672 100644
--- a/pkgs/ffigen/test/native_objc_test/block_test.dart
+++ b/pkgs/ffigen/test/native_objc_test/block_test.dart
@@ -115,19 +115,27 @@ void main() {
       expect(value, 123);
     });*/
 
-    // test('Blocking block same thread', () {
-    //   int value = 0;
-    //   final block = VoidBlock.blocking(() async {
-    //     await Future.delayed(Duration(milliseconds: 100));
-    //     value = 123;
-    //   });
-    //   BlockTester.callOnSameThread_(block);
-    //   expect(value, 123);
-    // });
+    void waitSync(Duration d) {
+      final t = Stopwatch();
+      t.start();
+      while (t.elapsed < d) {
+        // Waiting...
+      }
+    }
+
+    test('Blocking block same thread', () {
+      int value = 0;
+      final block = VoidBlock.blocking(() {
+        waitSync(Duration(milliseconds: 100));
+        value = 123;
+      });
+      BlockTester.callOnSameThread_(block);
+      expect(value, 123);
+    });
 
     test('Blocking block new thread', () async {
-      final block = IntPtrBlock.blocking((Pointer<Int32> result) async {
-        await Future.delayed(Duration(milliseconds: 100));
+      final block = IntPtrBlock.blocking((Pointer<Int32> result) {
+        waitSync(Duration(milliseconds: 100));
         result.value = 123456;
       }, timeout: Duration(seconds: 60));
       final resultCompleter = Completer<int>();
@@ -140,8 +148,8 @@ void main() {
 
     test('Blocking block timeout', () async {
       int value = 0;
-      final block = VoidBlock.blocking(() async {
-        await Future.delayed(Duration(milliseconds: 300));
+      final block = VoidBlock.blocking(() {
+        waitSync(Duration(milliseconds: 300));
         value = 123456;
       }, timeout: Duration(milliseconds: 100));
       BlockTester.callOnNewThread_(block).start();
diff --git a/pkgs/objective_c/lib/src/internal.dart b/pkgs/objective_c/lib/src/internal.dart
index 618bbca8a..4f9c9ce74 100644
--- a/pkgs/objective_c/lib/src/internal.dart
+++ b/pkgs/objective_c/lib/src/internal.dart
@@ -425,13 +425,15 @@ Function getBlockClosure(_BlkPtr block) {
 typedef _NewWaiterFn = NativeFunction<_VoidPtr Function()>;
 typedef _AwaitWaiterFn = NativeFunction<Void Function(_VoidPtr, Double)>;
 typedef _NativeWrapperFn = _BlkPtr Function(
-    _BlkPtr, double, Pointer<_NewWaiterFn>, Pointer<_AwaitWaiterFn>);
+    _BlkPtr, _BlkPtr, double, Pointer<_NewWaiterFn>, Pointer<_AwaitWaiterFn>);
 
 /// Only for use by ffigen bindings.
 _BlkPtr wrapBlockingBlock(
-        _NativeWrapperFn nativeWrapper, _BlkPtr raw, Duration timeout) =>
+        _NativeWrapperFn nativeWrapper, _BlkPtr raw, _BlkPtr rawListener,
+        Duration timeout) =>
     nativeWrapper(
       raw,
+      rawListener,
       timeout.inMicroseconds / Duration.microsecondsPerSecond,
       Native.addressOf<_NewWaiterFn>(c.newWaiter),
       Native.addressOf<_AwaitWaiterFn>(c.awaitWaiter),
diff --git a/pkgs/objective_c/lib/src/objective_c_bindings_generated.dart b/pkgs/objective_c/lib/src/objective_c_bindings_generated.dart
index 4f5c4c3b0..81a3edcd0 100644
--- a/pkgs/objective_c/lib/src/objective_c_bindings_generated.dart
+++ b/pkgs/objective_c/lib/src/objective_c_bindings_generated.dart
@@ -39,6 +39,7 @@ set NSLocalizedDescriptionKey(NSString value) {
 
 @ffi.Native<
     ffi.Pointer<objc.ObjCBlockImpl> Function(
+        ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Double,
         ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>>,
@@ -49,6 +50,7 @@ set NSLocalizedDescriptionKey(NSString value) {
 external ffi.Pointer<objc.ObjCBlockImpl>
     _ObjectiveCBindings_wrapBlockingBlock_18d6mda(
   ffi.Pointer<objc.ObjCBlockImpl> block,
+  ffi.Pointer<objc.ObjCBlockImpl> listnerBlock,
   double timeoutSeconds,
   ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>> newWaiter,
   ffi.Pointer<
@@ -59,6 +61,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 
 @ffi.Native<
     ffi.Pointer<objc.ObjCBlockImpl> Function(
+        ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Double,
         ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>>,
@@ -69,6 +72,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 external ffi.Pointer<objc.ObjCBlockImpl>
     _ObjectiveCBindings_wrapBlockingBlock_1j2nt86(
   ffi.Pointer<objc.ObjCBlockImpl> block,
+  ffi.Pointer<objc.ObjCBlockImpl> listnerBlock,
   double timeoutSeconds,
   ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>> newWaiter,
   ffi.Pointer<
@@ -79,6 +83,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 
 @ffi.Native<
     ffi.Pointer<objc.ObjCBlockImpl> Function(
+        ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Double,
         ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>>,
@@ -89,6 +94,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 external ffi.Pointer<objc.ObjCBlockImpl>
     _ObjectiveCBindings_wrapBlockingBlock_ovsamd(
   ffi.Pointer<objc.ObjCBlockImpl> block,
+  ffi.Pointer<objc.ObjCBlockImpl> listnerBlock,
   double timeoutSeconds,
   ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>> newWaiter,
   ffi.Pointer<
@@ -99,6 +105,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 
 @ffi.Native<
     ffi.Pointer<objc.ObjCBlockImpl> Function(
+        ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Double,
         ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>>,
@@ -109,6 +116,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 external ffi.Pointer<objc.ObjCBlockImpl>
     _ObjectiveCBindings_wrapBlockingBlock_wjovn7(
   ffi.Pointer<objc.ObjCBlockImpl> block,
+  ffi.Pointer<objc.ObjCBlockImpl> listnerBlock,
   double timeoutSeconds,
   ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>> newWaiter,
   ffi.Pointer<
@@ -119,6 +127,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 
 @ffi.Native<
     ffi.Pointer<objc.ObjCBlockImpl> Function(
+        ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Pointer<objc.ObjCBlockImpl>,
         ffi.Double,
         ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>>,
@@ -129,6 +138,7 @@ external ffi.Pointer<objc.ObjCBlockImpl>
 external ffi.Pointer<objc.ObjCBlockImpl>
     _ObjectiveCBindings_wrapBlockingBlock_wjvic9(
   ffi.Pointer<objc.ObjCBlockImpl> block,
+  ffi.Pointer<objc.ObjCBlockImpl> listnerBlock,
   double timeoutSeconds,
   ffi.Pointer<ffi.NativeFunction<ffi.Pointer<ffi.Void> Function()>> newWaiter,
   ffi.Pointer<
@@ -9472,14 +9482,14 @@ ffi.NativeCallable<
                 ffi.Pointer<objc.ObjCObject>)>.listener(
         _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_listenerTrampoline)
       ..keepIsolateAlive = false;
-Future<void>
+void
     _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_blockingTrampoline(
         ffi.Pointer<objc.ObjCBlockImpl> block,
         ffi.Pointer<ffi.Void> waiter,
         ffi.Pointer<objc.ObjCBlockImpl> arg0,
         ffi.Pointer<objc.ObjCObject> arg1,
-        ffi.Pointer<objc.ObjCObject> arg2) async {
-  await (objc.getBlockClosure(block) as FutureOr<void> Function(
+        ffi.Pointer<objc.ObjCObject> arg2) {
+  (objc.getBlockClosure(block) as void Function(
       ffi.Pointer<objc.ObjCBlockImpl>,
       ffi.Pointer<objc.ObjCObject>,
       ffi.Pointer<objc.ObjCObject>))(arg0, arg1, arg2);
@@ -9495,6 +9505,23 @@ ffi.NativeCallable<
             ffi.Pointer<objc.ObjCObject>,
             ffi.Pointer<objc.ObjCObject>)>
     _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_blockingCallable =
+    ffi.NativeCallable<
+            ffi.Void Function(
+                ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<objc.ObjCObject>,
+                ffi.Pointer<objc.ObjCObject>)>.isolateLocal(
+        _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_blockingTrampoline)
+      ..keepIsolateAlive = false;
+ffi.NativeCallable<
+        ffi.Void Function(
+            ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<objc.ObjCObject>,
+            ffi.Pointer<objc.ObjCObject>)>
+    _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_blockingListenerCallable =
     ffi.NativeCallable<
             ffi.Void Function(
                 ffi.Pointer<objc.ObjCBlockImpl>,
@@ -9629,9 +9656,26 @@ abstract final class ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCO
                 objc.ObjCObjectBase(arg1, retain: false, release: true),
                 NSDictionary.castFromPointer(arg2,
                     retain: false, release: true)));
+    final rawListener = objc.newClosureBlock(
+        _ObjCBlock_ffiVoid_NSItemProviderCompletionHandler_objcObjCObject_NSDictionary_blockingListenerCallable
+            .nativeFunction
+            .cast(),
+        (ffi.Pointer<objc.ObjCBlockImpl> arg0,
+                ffi.Pointer<objc.ObjCObject> arg1,
+                ffi.Pointer<objc.ObjCObject> arg2) =>
+            fn(
+                ObjCBlock_ffiVoid_objcObjCObject_NSError.castFromPointer(arg0,
+                    retain: false, release: true),
+                objc.ObjCObjectBase(arg1, retain: false, release: true),
+                NSDictionary.castFromPointer(arg2,
+                    retain: false, release: true)));
     final wrapper = objc.wrapBlockingBlock(
-        _ObjectiveCBindings_wrapBlockingBlock_1j2nt86, raw, timeout);
+        _ObjectiveCBindings_wrapBlockingBlock_1j2nt86,
+        raw,
+        rawListener,
+        timeout);
     objc.objectRelease(raw.cast());
+    objc.objectRelease(rawListener.cast());
     return objc.ObjCBlock<
         ffi.Void Function(
             objc.ObjCBlock<
@@ -9706,12 +9750,11 @@ ffi.NativeCallable<
                 ffi.Pointer<ffi.Void>)>.listener(
         _ObjCBlock_ffiVoid_ffiVoid_listenerTrampoline)
       ..keepIsolateAlive = false;
-Future<void> _ObjCBlock_ffiVoid_ffiVoid_blockingTrampoline(
+void _ObjCBlock_ffiVoid_ffiVoid_blockingTrampoline(
     ffi.Pointer<objc.ObjCBlockImpl> block,
     ffi.Pointer<ffi.Void> waiter,
-    ffi.Pointer<ffi.Void> arg0) async {
-  await (objc.getBlockClosure(block) as FutureOr<void> Function(
-      ffi.Pointer<ffi.Void>))(arg0);
+    ffi.Pointer<ffi.Void> arg0) {
+  (objc.getBlockClosure(block) as void Function(ffi.Pointer<ffi.Void>))(arg0);
   objc.signalWaiter(waiter);
   objc.objectRelease(block.cast());
 }
@@ -9720,6 +9763,14 @@ ffi.NativeCallable<
         ffi.Void Function(ffi.Pointer<objc.ObjCBlockImpl>,
             ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Void>)>
     _ObjCBlock_ffiVoid_ffiVoid_blockingCallable = ffi.NativeCallable<
+            ffi.Void Function(ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Void>)>.isolateLocal(
+        _ObjCBlock_ffiVoid_ffiVoid_blockingTrampoline)
+      ..keepIsolateAlive = false;
+ffi.NativeCallable<
+        ffi.Void Function(ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Void>)>
+    _ObjCBlock_ffiVoid_ffiVoid_blockingListenerCallable = ffi.NativeCallable<
             ffi.Void Function(ffi.Pointer<objc.ObjCBlockImpl>,
                 ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Void>)>.listener(
         _ObjCBlock_ffiVoid_ffiVoid_blockingTrampoline)
@@ -9789,9 +9840,17 @@ abstract final class ObjCBlock_ffiVoid_ffiVoid {
     final raw = objc.newClosureBlock(
         _ObjCBlock_ffiVoid_ffiVoid_blockingCallable.nativeFunction.cast(),
         (ffi.Pointer<ffi.Void> arg0) => fn(arg0));
+    final rawListener = objc.newClosureBlock(
+        _ObjCBlock_ffiVoid_ffiVoid_blockingListenerCallable.nativeFunction
+            .cast(),
+        (ffi.Pointer<ffi.Void> arg0) => fn(arg0));
     final wrapper = objc.wrapBlockingBlock(
-        _ObjectiveCBindings_wrapBlockingBlock_ovsamd, raw, timeout);
+        _ObjectiveCBindings_wrapBlockingBlock_ovsamd,
+        raw,
+        rawListener,
+        timeout);
     objc.objectRelease(raw.cast());
+    objc.objectRelease(rawListener.cast());
     return objc.ObjCBlock<ffi.Void Function(ffi.Pointer<ffi.Void>)>(wrapper,
         retain: false, release: true);
   }
@@ -9857,12 +9916,12 @@ ffi.NativeCallable<
                 ffi.Pointer<ffi.Void>, ffi.Pointer<objc.ObjCObject>)>.listener(
         _ObjCBlock_ffiVoid_ffiVoid_NSCoder_listenerTrampoline)
       ..keepIsolateAlive = false;
-Future<void> _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingTrampoline(
+void _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingTrampoline(
     ffi.Pointer<objc.ObjCBlockImpl> block,
     ffi.Pointer<ffi.Void> waiter,
     ffi.Pointer<ffi.Void> arg0,
-    ffi.Pointer<objc.ObjCObject> arg1) async {
-  await (objc.getBlockClosure(block) as FutureOr<void> Function(
+    ffi.Pointer<objc.ObjCObject> arg1) {
+  (objc.getBlockClosure(block) as void Function(
       ffi.Pointer<ffi.Void>, ffi.Pointer<objc.ObjCObject>))(arg0, arg1);
   objc.signalWaiter(waiter);
   objc.objectRelease(block.cast());
@@ -9875,6 +9934,21 @@ ffi.NativeCallable<
             ffi.Pointer<ffi.Void>,
             ffi.Pointer<objc.ObjCObject>)>
     _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingCallable = ffi.NativeCallable<
+            ffi.Void Function(
+                ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<objc.ObjCObject>)>.isolateLocal(
+        _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingTrampoline)
+      ..keepIsolateAlive = false;
+ffi.NativeCallable<
+        ffi.Void Function(
+            ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<objc.ObjCObject>)>
+    _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingListenerCallable = ffi
+        .NativeCallable<
             ffi.Void Function(
                 ffi.Pointer<objc.ObjCBlockImpl>,
                 ffi.Pointer<ffi.Void>,
@@ -9960,9 +10034,19 @@ abstract final class ObjCBlock_ffiVoid_ffiVoid_NSCoder {
             .cast(),
         (ffi.Pointer<ffi.Void> arg0, ffi.Pointer<objc.ObjCObject> arg1) => fn(
             arg0, NSCoder.castFromPointer(arg1, retain: false, release: true)));
+    final rawListener = objc.newClosureBlock(
+        _ObjCBlock_ffiVoid_ffiVoid_NSCoder_blockingListenerCallable
+            .nativeFunction
+            .cast(),
+        (ffi.Pointer<ffi.Void> arg0, ffi.Pointer<objc.ObjCObject> arg1) => fn(
+            arg0, NSCoder.castFromPointer(arg1, retain: false, release: true)));
     final wrapper = objc.wrapBlockingBlock(
-        _ObjectiveCBindings_wrapBlockingBlock_wjovn7, raw, timeout);
+        _ObjectiveCBindings_wrapBlockingBlock_wjovn7,
+        raw,
+        rawListener,
+        timeout);
     objc.objectRelease(raw.cast());
+    objc.objectRelease(rawListener.cast());
     return objc.ObjCBlock<ffi.Void Function(ffi.Pointer<ffi.Void>, NSCoder)>(
         wrapper,
         retain: false,
@@ -10053,17 +10137,14 @@ ffi.NativeCallable<
                 ffi.UnsignedLong)>.listener(
         _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_listenerTrampoline)
       ..keepIsolateAlive = false;
-Future<void>
-    _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingTrampoline(
-        ffi.Pointer<objc.ObjCBlockImpl> block,
-        ffi.Pointer<ffi.Void> waiter,
-        ffi.Pointer<ffi.Void> arg0,
-        ffi.Pointer<objc.ObjCObject> arg1,
-        int arg2) async {
-  await (objc.getBlockClosure(block) as FutureOr<void> Function(
-      ffi.Pointer<ffi.Void>,
-      ffi.Pointer<objc.ObjCObject>,
-      int))(arg0, arg1, arg2);
+void _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingTrampoline(
+    ffi.Pointer<objc.ObjCBlockImpl> block,
+    ffi.Pointer<ffi.Void> waiter,
+    ffi.Pointer<ffi.Void> arg0,
+    ffi.Pointer<objc.ObjCObject> arg1,
+    int arg2) {
+  (objc.getBlockClosure(block) as void Function(ffi.Pointer<ffi.Void>,
+      ffi.Pointer<objc.ObjCObject>, int))(arg0, arg1, arg2);
   objc.signalWaiter(waiter);
   objc.objectRelease(block.cast());
 }
@@ -10076,6 +10157,23 @@ ffi.NativeCallable<
             ffi.Pointer<objc.ObjCObject>,
             ffi.UnsignedLong)>
     _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingCallable =
+    ffi.NativeCallable<
+            ffi.Void Function(
+                ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<objc.ObjCObject>,
+                ffi.UnsignedLong)>.isolateLocal(
+        _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingTrampoline)
+      ..keepIsolateAlive = false;
+ffi.NativeCallable<
+        ffi.Void Function(
+            ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<objc.ObjCObject>,
+            ffi.UnsignedLong)>
+    _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingListenerCallable =
     ffi.NativeCallable<
             ffi.Void Function(
                 ffi.Pointer<objc.ObjCBlockImpl>,
@@ -10177,9 +10275,23 @@ abstract final class ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent {
                 arg0,
                 NSStream.castFromPointer(arg1, retain: false, release: true),
                 NSStreamEvent.fromValue(arg2)));
+    final rawListener = objc.newClosureBlock(
+        _ObjCBlock_ffiVoid_ffiVoid_NSStream_NSStreamEvent_blockingListenerCallable
+            .nativeFunction
+            .cast(),
+        (ffi.Pointer<ffi.Void> arg0, ffi.Pointer<objc.ObjCObject> arg1,
+                int arg2) =>
+            fn(
+                arg0,
+                NSStream.castFromPointer(arg1, retain: false, release: true),
+                NSStreamEvent.fromValue(arg2)));
     final wrapper = objc.wrapBlockingBlock(
-        _ObjectiveCBindings_wrapBlockingBlock_18d6mda, raw, timeout);
+        _ObjectiveCBindings_wrapBlockingBlock_18d6mda,
+        raw,
+        rawListener,
+        timeout);
     objc.objectRelease(raw.cast());
+    objc.objectRelease(rawListener.cast());
     return objc.ObjCBlock<
         ffi.Void Function(ffi.Pointer<ffi.Void>, NSStream,
             ffi.UnsignedLong)>(wrapper, retain: false, release: true);
@@ -10262,12 +10374,12 @@ ffi.NativeCallable<
                 ffi.Pointer<objc.ObjCObject>)>.listener(
         _ObjCBlock_ffiVoid_objcObjCObject_NSError_listenerTrampoline)
       ..keepIsolateAlive = false;
-Future<void> _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingTrampoline(
+void _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingTrampoline(
     ffi.Pointer<objc.ObjCBlockImpl> block,
     ffi.Pointer<ffi.Void> waiter,
     ffi.Pointer<objc.ObjCObject> arg0,
-    ffi.Pointer<objc.ObjCObject> arg1) async {
-  await (objc.getBlockClosure(block) as FutureOr<void> Function(
+    ffi.Pointer<objc.ObjCObject> arg1) {
+  (objc.getBlockClosure(block) as void Function(
       ffi.Pointer<objc.ObjCObject>, ffi.Pointer<objc.ObjCObject>))(arg0, arg1);
   objc.signalWaiter(waiter);
   objc.objectRelease(block.cast());
@@ -10280,6 +10392,21 @@ ffi.NativeCallable<
             ffi.Pointer<objc.ObjCObject>,
             ffi.Pointer<objc.ObjCObject>)>
     _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingCallable = ffi
+        .NativeCallable<
+            ffi.Void Function(
+                ffi.Pointer<objc.ObjCBlockImpl>,
+                ffi.Pointer<ffi.Void>,
+                ffi.Pointer<objc.ObjCObject>,
+                ffi.Pointer<objc.ObjCObject>)>.isolateLocal(
+        _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingTrampoline)
+      ..keepIsolateAlive = false;
+ffi.NativeCallable<
+        ffi.Void Function(
+            ffi.Pointer<objc.ObjCBlockImpl>,
+            ffi.Pointer<ffi.Void>,
+            ffi.Pointer<objc.ObjCObject>,
+            ffi.Pointer<objc.ObjCObject>)>
+    _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingListenerCallable = ffi
         .NativeCallable<
             ffi.Void Function(
                 ffi.Pointer<objc.ObjCBlockImpl>,
@@ -10381,9 +10508,24 @@ abstract final class ObjCBlock_ffiVoid_objcObjCObject_NSError {
                     ? null
                     : objc.ObjCObjectBase(arg0, retain: false, release: true),
                 NSError.castFromPointer(arg1, retain: false, release: true)));
+    final rawListener = objc.newClosureBlock(
+        _ObjCBlock_ffiVoid_objcObjCObject_NSError_blockingListenerCallable
+            .nativeFunction
+            .cast(),
+        (ffi.Pointer<objc.ObjCObject> arg0,
+                ffi.Pointer<objc.ObjCObject> arg1) =>
+            fn(
+                arg0.address == 0
+                    ? null
+                    : objc.ObjCObjectBase(arg0, retain: false, release: true),
+                NSError.castFromPointer(arg1, retain: false, release: true)));
     final wrapper = objc.wrapBlockingBlock(
-        _ObjectiveCBindings_wrapBlockingBlock_wjvic9, raw, timeout);
+        _ObjectiveCBindings_wrapBlockingBlock_wjvic9,
+        raw,
+        rawListener,
+        timeout);
     objc.objectRelease(raw.cast());
+    objc.objectRelease(rawListener.cast());
     return objc.ObjCBlock<
             ffi.Void Function(ffi.Pointer<objc.ObjCObject>?, NSError)>(wrapper,
         retain: false, release: true);
diff --git a/pkgs/objective_c/src/objective_c.m b/pkgs/objective_c/src/objective_c.m
index 63d44374f..41b35063b 100644
--- a/pkgs/objective_c/src/objective_c.m
+++ b/pkgs/objective_c/src/objective_c.m
@@ -59,20 +59,20 @@ -(void)wait: (double)timeoutSeconds {
 @end
 
 FFI_EXPORT void* DOBJC_newWaiter() {
-  DOBJCWaiter* wait = [[DOBJCWaiter alloc] init];
+  DOBJCWaiter* w = [[DOBJCWaiter alloc] init];
   // __bridge_retained increments the ref count, __bridge_transfer decrements
   // it, and __bridge doesn't change it. One of the __bridge_retained calls is
   // balanced by the __bridge_transfer in signalWaiter, and the other is
   // balanced by the one in awaitWaiter. In other words, this function returns
   // an object with a +2 ref count, and signal and await each decrement the
   // ref count.
-  return (__bridge_retained void*)(__bridge id)(__bridge_retained void*)(wait);
+  return (__bridge_retained void*)(__bridge id)(__bridge_retained void*)(w);
 }
 
-FFI_EXPORT void DOBJC_signalWaiter(void* wait) {
-  [(__bridge_transfer DOBJCWaiter*)wait signal];
+FFI_EXPORT void DOBJC_signalWaiter(void* waiter) {
+  if (waiter) [(__bridge_transfer DOBJCWaiter*)waiter signal];
 }
 
-FFI_EXPORT void DOBJC_awaitWaiter(void* wait, double timeoutSeconds) {
-  [(__bridge_transfer DOBJCWaiter*)wait wait: timeoutSeconds];
+FFI_EXPORT void DOBJC_awaitWaiter(void* waiter, double timeoutSeconds) {
+  [(__bridge_transfer DOBJCWaiter*)waiter wait: timeoutSeconds];
 }
diff --git a/pkgs/objective_c/src/objective_c_bindings_generated.m b/pkgs/objective_c/src/objective_c_bindings_generated.m
index 8285f4691..0366e9949 100644
--- a/pkgs/objective_c/src/objective_c_bindings_generated.m
+++ b/pkgs/objective_c/src/objective_c_bindings_generated.m
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#import <Foundation/Foundation.h>
 #import "foundation.h"
 #import "input_stream_adapter.h"
 #import "proxy.h"
@@ -24,13 +25,20 @@ _ListenerTrampoline _ObjectiveCBindings_wrapListenerBlock_1j2nt86(_ListenerTramp
 typedef void  (^_BlockingTrampoline)(void * waiter, id arg0, id arg1, id arg2);
 __attribute__((visibility("default"))) __attribute__((used))
 _ListenerTrampoline _ObjectiveCBindings_wrapBlockingBlock_1j2nt86(
-    _BlockingTrampoline block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    _BlockingTrampoline block, _BlockingTrampoline listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void(id arg0, id arg1, id arg2) {
-    void* waiter = newWaiter();
-    objc_retainBlock(block);
-    block(waiter, objc_retainBlock(arg0), objc_retain(arg1), objc_retain(arg2));
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      objc_retainBlock(block);
+      block(nil, objc_retainBlock(arg0), objc_retain(arg1), objc_retain(arg2));
+    } else {
+      void* waiter = newWaiter();
+      objc_retainBlock(listenerBlock);
+      listenerBlock(waiter, objc_retainBlock(arg0), objc_retain(arg1), objc_retain(arg2));
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }
 
@@ -46,13 +54,20 @@ _ListenerTrampoline1 _ObjectiveCBindings_wrapListenerBlock_ovsamd(_ListenerTramp
 typedef void  (^_BlockingTrampoline1)(void * waiter, void * arg0);
 __attribute__((visibility("default"))) __attribute__((used))
 _ListenerTrampoline1 _ObjectiveCBindings_wrapBlockingBlock_ovsamd(
-    _BlockingTrampoline1 block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    _BlockingTrampoline1 block, _BlockingTrampoline1 listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void(void * arg0) {
-    void* waiter = newWaiter();
-    objc_retainBlock(block);
-    block(waiter, arg0);
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      objc_retainBlock(block);
+      block(nil, arg0);
+    } else {
+      void* waiter = newWaiter();
+      objc_retainBlock(listenerBlock);
+      listenerBlock(waiter, arg0);
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }
 
@@ -68,13 +83,20 @@ _ListenerTrampoline2 _ObjectiveCBindings_wrapListenerBlock_wjovn7(_ListenerTramp
 typedef void  (^_BlockingTrampoline2)(void * waiter, void * arg0, id arg1);
 __attribute__((visibility("default"))) __attribute__((used))
 _ListenerTrampoline2 _ObjectiveCBindings_wrapBlockingBlock_wjovn7(
-    _BlockingTrampoline2 block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    _BlockingTrampoline2 block, _BlockingTrampoline2 listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void(void * arg0, id arg1) {
-    void* waiter = newWaiter();
-    objc_retainBlock(block);
-    block(waiter, arg0, objc_retain(arg1));
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      objc_retainBlock(block);
+      block(nil, arg0, objc_retain(arg1));
+    } else {
+      void* waiter = newWaiter();
+      objc_retainBlock(listenerBlock);
+      listenerBlock(waiter, arg0, objc_retain(arg1));
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }
 
@@ -90,13 +112,20 @@ _ListenerTrampoline3 _ObjectiveCBindings_wrapListenerBlock_18d6mda(_ListenerTram
 typedef void  (^_BlockingTrampoline3)(void * waiter, void * arg0, id arg1, NSStreamEvent arg2);
 __attribute__((visibility("default"))) __attribute__((used))
 _ListenerTrampoline3 _ObjectiveCBindings_wrapBlockingBlock_18d6mda(
-    _BlockingTrampoline3 block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    _BlockingTrampoline3 block, _BlockingTrampoline3 listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void(void * arg0, id arg1, NSStreamEvent arg2) {
-    void* waiter = newWaiter();
-    objc_retainBlock(block);
-    block(waiter, arg0, objc_retain(arg1), arg2);
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      objc_retainBlock(block);
+      block(nil, arg0, objc_retain(arg1), arg2);
+    } else {
+      void* waiter = newWaiter();
+      objc_retainBlock(listenerBlock);
+      listenerBlock(waiter, arg0, objc_retain(arg1), arg2);
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }
 
@@ -112,12 +141,19 @@ _ListenerTrampoline4 _ObjectiveCBindings_wrapListenerBlock_wjvic9(_ListenerTramp
 typedef void  (^_BlockingTrampoline4)(void * waiter, id arg0, id arg1);
 __attribute__((visibility("default"))) __attribute__((used))
 _ListenerTrampoline4 _ObjectiveCBindings_wrapBlockingBlock_wjvic9(
-    _BlockingTrampoline4 block, double timeoutSeconds, void* (*newWaiter)(),
-    void (*awaitWaiter)(void*, double)) NS_RETURNS_RETAINED {
+    _BlockingTrampoline4 block, _BlockingTrampoline4 listenerBlock, double timeoutSeconds,
+    void* (*newWaiter)(), void (*awaitWaiter)(void*, double))
+        NS_RETURNS_RETAINED {
+  NSThread *targetThread = [NSThread currentThread];
   return ^void(id arg0, id arg1) {
-    void* waiter = newWaiter();
-    objc_retainBlock(block);
-    block(waiter, objc_retain(arg0), objc_retain(arg1));
-    awaitWaiter(waiter, timeoutSeconds);
+    if ([NSThread currentThread] == targetThread) {
+      objc_retainBlock(block);
+      block(nil, objc_retain(arg0), objc_retain(arg1));
+    } else {
+      void* waiter = newWaiter();
+      objc_retainBlock(listenerBlock);
+      listenerBlock(waiter, objc_retain(arg0), objc_retain(arg1));
+      awaitWaiter(waiter, timeoutSeconds);
+    }
   };
 }