diff --git a/docs/release-notes.md b/docs/release-notes.md
index 4ca11f01..585644ef 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -11,6 +11,9 @@
 * For console commands:
   * Fixed `player_add` with Journal Scraps and Secret Notes.
 
+* For the web UI:
+  * Fixed JSON validator warning for update keys without a subkey.
+
 ## 3.13.4
 Released 16 January 2022 for Stardew Valley 1.5.6 or later.
 
diff --git a/src/SMAPI.Web/wwwroot/schemas/manifest.json b/src/SMAPI.Web/wwwroot/schemas/manifest.json
index b6722347..7457b993 100644
--- a/src/SMAPI.Web/wwwroot/schemas/manifest.json
+++ b/src/SMAPI.Web/wwwroot/schemas/manifest.json
@@ -103,7 +103,7 @@
             "type": "array",
             "items": {
                 "type": "string",
-                "pattern": "^(?i)(Chucklefish:\\d+|Nexus:\\d+|GitHub:[A-Za-z0-9_\\-]+/[A-Za-z0-9_\\-]+|ModDrop:\\d+)(?: *@ *[a-zA-Z0-9_]+ *)$",
+                "pattern": "^(?i)(Chucklefish:\\d+|Nexus:\\d+|GitHub:[A-Za-z0-9_\\-]+/[A-Za-z0-9_\\-]+|ModDrop:\\d+)(?: *@ *[a-zA-Z0-9_]+ *)?$",
                 "@errorMessages": {
                     "pattern": "Invalid update key; see https://stardewvalleywiki.com/Modding:Modder_Guide/APIs/Manifest#Update_checks for more info."
                 }