diff --git a/src/microdot/sse.py b/src/microdot/sse.py
index 0e3396c..4e17a68 100644
--- a/src/microdot/sse.py
+++ b/src/microdot/sse.py
@@ -8,13 +8,23 @@ class SSE:
         self.queue = []
 
     async def send(self, data, event=None):
+        """Send an event to the client.
+
+        :param data: the data to send. It can be given as a string, bytes, dict
+                     or list. Dictionaries and lists are serialized to JSON.
+                     Any other types are converted to string before sending.
+        :param event: an optional event name, to send along with the data. If
+                      given, it must be a string.
+        """
         if isinstance(data, (dict, list)):
-            data = json.dumps(data)
-        elif not isinstance(data, str):
-            data = str(data)
-        data = f'data: {data}\n\n'
+            data = json.dumps(data).encode()
+        elif isinstance(data, str):
+            data = data.encode()
+        elif not isinstance(data, bytes):
+            data = str(data).encode()
+        data = b'data: ' + data + b'\n\n'
         if event:
-            data = f'event: {event}\n{data}'
+            data = b'event: ' + event.encode() + b'\n' + data
         self.queue.append(data)
         self.event.set()
 
diff --git a/tests/test_sse.py b/tests/test_sse.py
index edebf11..be67b59 100644
--- a/tests/test_sse.py
+++ b/tests/test_sse.py
@@ -26,6 +26,7 @@ class TestWebSocket(unittest.TestCase):
             await sse.send({'foo': 'bar'})
             await sse.send([42, 'foo', 'bar'])
             await sse.send(ValueError('foo'))
+            await sse.send(b'foo')
 
         client = TestClient(app)
         response = self._run(client.get('/sse'))
@@ -35,4 +36,5 @@ class TestWebSocket(unittest.TestCase):
                                          'event: test\ndata: bar\n\n'
                                          'data: {"foo": "bar"}\n\n'
                                          'data: [42, "foo", "bar"]\n\n'
+                                         'data: foo\n\n'
                                          'data: foo\n\n'))