diff --git a/tests/test_http_response.py b/tests/test_http_response.py
index 4f514e0..2efc4ec 100644
--- a/tests/test_http_response.py
+++ b/tests/test_http_response.py
@@ -16,7 +16,7 @@ class TestHTTPResponse(DaphneTestCase):
         Lowercases and sorts headers, and strips transfer-encoding ones.
         """
         return sorted([
-            (name.lower(), value)
+            (name.lower(), value.strip())
             for name, value in headers
             if name.lower() != "transfer-encoding"
         ])
diff --git a/tests/test_websocket.py b/tests/test_websocket.py
index af967fa..409aac4 100644
--- a/tests/test_websocket.py
+++ b/tests/test_websocket.py
@@ -52,7 +52,7 @@ class TestWebsocket(DaphneTestCase):
         # {name: [value1, value2, ...]} and check if they're equal.
         transformed_scope_headers = collections.defaultdict(list)
         for name, value in scope["headers"]:
-            transformed_scope_headers[name] = []
+            transformed_scope_headers.setdefault(name, [])
             # Make sure to split out any headers collapsed with commas
             for bit in value.split(b","):
                 if bit.strip():
@@ -61,8 +61,8 @@ class TestWebsocket(DaphneTestCase):
         for name, value in (headers or []):
             expected_name = name.lower().strip().encode("ascii")
             expected_value = value.strip().encode("ascii")
-            transformed_request_headers[expected_name] = []
             # Make sure to split out any headers collapsed with commas
+            transformed_request_headers.setdefault(expected_name, [])
             for bit in expected_value.split(b","):
                 if bit.strip():
                     transformed_request_headers[expected_name].append(bit.strip())