diff --git a/src/lune/scheduler/impl_async.rs b/src/lune/scheduler/impl_async.rs
index 6f9a83e..fb3d0a8 100644
--- a/src/lune/scheduler/impl_async.rs
+++ b/src/lune/scheduler/impl_async.rs
@@ -14,10 +14,10 @@ where
     where
         F: Future<Output = ()> + 'fut,
     {
-        let futs = self
-            .futures
-            .try_lock()
-            .expect("Failed to lock futures queue");
+        let futs = self.futures.try_lock().expect(
+            "Failed to lock futures queue - \
+            make sure not to schedule futures during futures resumption",
+        );
         futs.push(Box::pin(fut))
     }
 
diff --git a/tests/globals/pcall.luau b/tests/globals/pcall.luau
index 7293879..fa983cb 100644
--- a/tests/globals/pcall.luau
+++ b/tests/globals/pcall.luau
@@ -7,7 +7,10 @@ local PORT = 9090 -- NOTE: This must be different from
 local function test(f, ...)
 	local success, message = pcall(f, ...)
 	assert(not success, "Function did not throw an error")
-	assert(type(message) == "userdata", "Pcall did not return a proper error")
+	assert(
+		type(message) == "string" or type(message) == "userdata",
+		"Pcall did not return a proper error"
+	)
 end
 
 -- These are not async but should be pcallable
@@ -24,7 +27,7 @@ local handle = net.serve(PORT, function()
 	return ""
 end)
 
-task.delay(0, function()
+task.delay(0.25, function()
 	handle.stop()
 end)