diff --git a/tests/tests_asyncio.py b/tests/tests_asyncio.py
index 5311701..513066d 100644
--- a/tests/tests_asyncio.py
+++ b/tests/tests_asyncio.py
@@ -120,6 +120,26 @@ async def test_as_completed(capsys, tol):
                 raise
 
 
+@mark.asyncio
+async def test_as_completed_unsized(capsys):
+    """Test asyncio as_completed with an unsized iterable"""
+    fs = (asyncio.sleep(0, result=i) for i in range(3))
+    res = sorted([await f for f in as_completed(fs)])
+    assert res == [0, 1, 2]
+    _, err = capsys.readouterr()
+    assert '3it' in err
+
+
+@mark.asyncio
+async def test_as_completed_unsized_with_total(capsys):
+    """Test asyncio as_completed with an unsized iterable and an explicit total"""
+    fs = (asyncio.sleep(0, result=i) for i in range(3))
+    res = sorted([await f for f in as_completed(fs, total=3)])
+    assert res == [0, 1, 2]
+    _, err = capsys.readouterr()
+    assert '3/3' in err
+
+
 async def double(i):
     return i * 2
 
diff --git a/tqdm/asyncio.py b/tqdm/asyncio.py
index ac5c2e6..df7ef5a 100644
--- a/tqdm/asyncio.py
+++ b/tqdm/asyncio.py
@@ -64,7 +64,10 @@ class tqdm_asyncio(std_tqdm):
         Wrapper for `asyncio.as_completed`.
         """
         if total is None:
-            total = len(fs)
+            try:
+                total = len(fs)
+            except (TypeError, AttributeError):
+                total = None
         kwargs = {}
         if version_info[:2] < (3, 10):
             kwargs['loop'] = loop