diff --git a/src/requirements.txt b/src/requirements.txt
index c6b0d218..b88b3f22 100644
--- a/src/requirements.txt
+++ b/src/requirements.txt
@@ -16,4 +16,6 @@ django-filter~=2.2.0
 channels~=2.4.0
 channels-redis~=2.4.2
 twilio~=6.45.4
+
+# Transitive dependency, pinned to fix an error. See: https://github.com/tl-its-umich-edu/remote-office-hours-queue/issues/331
 twisted<21