diff --git a/changelogs/server_server/newsfragments/2334.clarification b/changelogs/server_server/newsfragments/2334.clarification
new file mode 100644
index 00000000..5ea52dc3
--- /dev/null
+++ b/changelogs/server_server/newsfragments/2334.clarification
@@ -0,0 +1 @@
+Clarify that server ACLs are case-insensitive.
\ No newline at end of file
diff --git a/data/event-schemas/schema/m.room.server_acl.yaml b/data/event-schemas/schema/m.room.server_acl.yaml
index da490452..9ae60114 100644
--- a/data/event-schemas/schema/m.room.server_acl.yaml
+++ b/data/event-schemas/schema/m.room.server_acl.yaml
@@ -62,7 +62,7 @@ properties:
       allow:
         type: array
         description: |-
-          The server names to allow in the room, excluding any port information.
+          The case-insensitive server names to allow in the room, excluding any port information.
           Each entry is interpreted as a [glob-style pattern](/appendices#glob-style-matching).
 
           **This defaults to an empty list when not provided, effectively disallowing
@@ -72,7 +72,7 @@ properties:
       deny:
         type: array
         description: |-
-          The server names to disallow in the room, excluding any port information.
+          The case-insensitive server names to disallow in the room, excluding any port information.
           Each entry is interpreted as a [glob-style pattern](/appendices#glob-style-matching).
 
           This defaults to an empty list when not provided.