diff --git a/tools/oldest_constraints.txt b/tools/oldest_constraints.txt
index 8dd96dfea..80fce8b33 100644
--- a/tools/oldest_constraints.txt
+++ b/tools/oldest_constraints.txt
@@ -51,5 +51,7 @@ funcsigs==0.4
 zope.hookable==4.0.4
 
 # Plugin constraints
+# These aren't necessarily the oldest versions we need to support
+# Tracking at https://github.com/certbot/certbot/issues/6473
 boto3==1.4.7
 botocore==1.7.41