diff --git a/disco/api/client.py b/disco/api/client.py
index 56423a5..d67dadf 100644
--- a/disco/api/client.py
+++ b/disco/api/client.py
@@ -26,7 +26,7 @@ def optional(**kwargs):
 
 
 def _reason_header(value):
-    return optional(**{'X-Audit-Log-Reason': quote(to_bytes(value))})
+    return optional(**{'X-Audit-Log-Reason': quote(to_bytes(value)) if value else None})
 
 
 class APIClient(LoggingClass):
diff --git a/tests/test_reason.py b/tests/test_reason.py
index bced948..4582467 100644
--- a/tests/test_reason.py
+++ b/tests/test_reason.py
@@ -9,3 +9,11 @@ class TestReason(TestCase):
 
         _, kwargs = api.http.calls[0]
         self.assertEqual(kwargs['headers']['X-Audit-Log-Reason'], 'yo%20%F0%9F%92%BF%20test')
+
+    def test_null_reason(self):
+        from tests.utils import TestAPIClient
+        api = TestAPIClient()
+        api.guilds_channels_modify(1, 2, 3, reason=None)
+
+        _, kwargs = api.http.calls[0]
+        self.assertFalse('X-Audit-Log-Reason' in kwargs['headers'])