diff --git a/Userland/Libraries/LibJS/Runtime/ArrayConstructor.cpp b/Userland/Libraries/LibJS/Runtime/ArrayConstructor.cpp
index ef538d0b7c7..37da813c0e1 100644
--- a/Userland/Libraries/LibJS/Runtime/ArrayConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ArrayConstructor.cpp
@@ -306,7 +306,7 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayConstructor::from_async)
     auto promise_capability = MUST(new_promise_capability(vm, realm.intrinsics().promise_constructor()));
 
     // 3. Let fromAsyncClosure be a new Abstract Closure with no parameters that captures C, mapfn, and thisArg and performs the following steps when called:
-    SafeFunction<Completion()> from_async_closure = [constructor, mapfn, this_arg, &vm, &realm, async_items]() mutable -> Completion {
+    auto from_async_closure = create_heap_function(realm.heap(), [constructor, mapfn, this_arg, &vm, &realm, async_items]() mutable -> Completion {
         bool mapping;
 
         // a. If mapfn is undefined, let mapping be false.
@@ -510,10 +510,10 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayConstructor::from_async)
             // ix. Return Completion Record { [[Type]]: return, [[Value]]: A, [[Target]]: empty }.
             return Completion { Completion::Type::Return, array };
         }
-    };
+    });
 
     // 4. Perform AsyncFunctionStart(promiseCapability, fromAsyncClosure).
-    async_function_start(vm, promise_capability, from_async_closure);
+    async_function_start(vm, promise_capability, *from_async_closure);
 
     // 5. Return promiseCapability.[[Promise]].
     return promise_capability->promise();
diff --git a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
index e9ac7a03afa..c6123c4389c 100644
--- a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
@@ -734,7 +734,7 @@ void async_block_start(VM& vm, T const& async_body, PromiseCapability const& pro
         Completion result;
 
         // a. If asyncBody is a Parse Node, then
-        if constexpr (!IsCallableWithArguments<T, Completion>) {
+        if constexpr (!IsSame<T, HeapFunction<Completion()>>) {
             // a. Let result be the result of evaluating asyncBody.
             // FIXME: Cache this executable somewhere.
             auto maybe_executable = Bytecode::compile(vm, async_body, FunctionKind::Async, "AsyncBlockStart"sv);
@@ -746,10 +746,8 @@ void async_block_start(VM& vm, T const& async_body, PromiseCapability const& pro
         // b. Else,
         else {
             // i. Assert: asyncBody is an Abstract Closure with no parameters.
-            static_assert(IsCallableWithArguments<T, Completion>);
-
             // ii. Let result be asyncBody().
-            result = async_body();
+            result = async_body.function()();
         }
 
         // c. Assert: If we return here, the async function either threw an exception or performed an implicit or explicit return; all awaiting is done.
@@ -811,8 +809,8 @@ void async_block_start(VM& vm, T const& async_body, PromiseCapability const& pro
 template void async_block_start(VM&, NonnullRefPtr<Statement const> const& async_body, PromiseCapability const&, ExecutionContext&);
 template void async_function_start(VM&, PromiseCapability const&, NonnullRefPtr<Statement const> const& async_function_body);
 
-template void async_block_start(VM&, SafeFunction<Completion()> const& async_body, PromiseCapability const&, ExecutionContext&);
-template void async_function_start(VM&, PromiseCapability const&, SafeFunction<Completion()> const& async_function_body);
+template void async_block_start(VM&, HeapFunction<Completion()> const& async_body, PromiseCapability const&, ExecutionContext&);
+template void async_function_start(VM&, PromiseCapability const&, HeapFunction<Completion()> const& async_function_body);
 
 // 10.2.1.4 OrdinaryCallEvaluateBody ( F, argumentsList ), https://tc39.es/ecma262/#sec-ordinarycallevaluatebody
 // 15.8.4 Runtime Semantics: EvaluateAsyncFunctionBody, https://tc39.es/ecma262/#sec-runtime-semantics-evaluatefunctionbody