diff --git a/src/microdot/asgi.py b/src/microdot/asgi.py
index caf5b47..2b1e88f 100644
--- a/src/microdot/asgi.py
+++ b/src/microdot/asgi.py
@@ -130,6 +130,8 @@ class Microdot(BaseMicrodot):
         try:
             while not cancelled:  # pragma: no branch
                 res_body = await body_iter.__anext__()
+                if isinstance(res_body, str):
+                    res_body = res_body.encode()
                 await send({'type': 'http.response.body',
                             'body': res_body,
                             'more_body': True})
diff --git a/tests/test_asgi.py b/tests/test_asgi.py
index d2d2e04..80bed02 100644
--- a/tests/test_asgi.py
+++ b/tests/test_asgi.py
@@ -35,7 +35,7 @@ class TestASGI(unittest.TestCase):
             class R:
                 def __init__(self):
                     self.i = 0
-                    self.body = [b're', b'sp', b'on', b'se', b'']
+                    self.body = [b're', b'sp', b'on', 'se', b'']
 
                 async def read(self, n):
                     data = self.body[self.i]