diff --git a/grpclib/client.py b/grpclib/client.py
index d55bf5d..b5c156f 100644
--- a/grpclib/client.py
+++ b/grpclib/client.py
@@ -587,8 +587,14 @@ class Channel:
         self._codec = codec
         self._status_details_codec = status_details_codec
 
-        self._config = H2Configuration(client_side=True,
-                                       header_encoding='ascii')
+        self._config = H2Configuration(
+            client_side=True,
+            header_encoding='ascii',
+            validate_inbound_headers=False,
+            validate_outbound_headers=False,
+            normalize_inbound_headers=False,
+            normalize_outbound_headers=False,
+        )
         self._authority = '{}:{}'.format(self._host, self._port)
 
         if ssl is True:
diff --git a/grpclib/server.py b/grpclib/server.py
index 3b29188..a01364e 100644
--- a/grpclib/server.py
+++ b/grpclib/server.py
@@ -582,6 +582,10 @@ class Server(_GC, asyncio.AbstractServer):
         self._config = h2.config.H2Configuration(
             client_side=False,
             header_encoding='ascii',
+            validate_inbound_headers=False,
+            validate_outbound_headers=False,
+            normalize_inbound_headers=False,
+            normalize_outbound_headers=False,
         )
 
         self._server: Optional[asyncio.AbstractServer] = None