diff --git a/parfive/downloader.py b/parfive/downloader.py
index 3967203..546bb1d 100644
--- a/parfive/downloader.py
+++ b/parfive/downloader.py
@@ -284,7 +284,7 @@ async def run_download(self):
 
     def _format_results(self, retvals, main_pb):
         # Squash all nested lists into a single flat list
-        if retvals:
+        if retvals and isinstance(retvals[0], list):
             retvals = list(reduce(list.__add__, retvals))
         errors = sum([isinstance(i, FailedDownload) for i in retvals])
         if errors:
@@ -435,23 +435,28 @@ async def _run_ftp_download(self, main_pb):
 
     async def _run_from_queue(self, queue, tokens, main_pb, *, session=None):
         futures = []
-        while not queue.empty():
-            get_file = await queue.get()
-            token = await tokens.get()
-            file_pb = self.tqdm if self.config.file_progress else False
-            future = asyncio.create_task(get_file(session, token=token, file_pb=file_pb))
-
-            def callback(token, future, main_pb):
-                try:
-                    tokens.put_nowait(token)
-                    # Update the main progressbar
-                    if main_pb and not future.exception():
-                        main_pb.update(1)
-                except asyncio.CancelledError:
-                    return
-
-            future.add_done_callback(partial(callback, token, main_pb=main_pb))
-            futures.append(future)
+        try:
+            while not queue.empty():
+                get_file = await queue.get()
+                token = await tokens.get()
+                file_pb = self.tqdm if self.config.file_progress else False
+                future = asyncio.create_task(get_file(session, token=token, file_pb=file_pb))
+
+                def callback(token, future, main_pb):
+                    try:
+                        tokens.put_nowait(token)
+                        # Update the main progressbar
+                        if main_pb and not future.exception():
+                            main_pb.update(1)
+                    except asyncio.CancelledError:
+                        return
+
+                future.add_done_callback(partial(callback, token, main_pb=main_pb))
+                futures.append(future)
+
+        except asyncio.CancelledError:
+            for task in futures:
+                task.cancel()
 
         return futures