diff --git a/Assets/Fungus/Docs/CHANGELOG.txt b/Assets/Fungus/Docs/CHANGELOG.txt
index cb5241ec6..b92173508 100644
--- a/Assets/Fungus/Docs/CHANGELOG.txt
+++ b/Assets/Fungus/Docs/CHANGELOG.txt
@@ -1,6 +1,13 @@
 Changelog {#changelog}
 =========
 
+v3.13.1
+======
+
+## Fixed
+
+- Build error in JsonChecker caused by missing asmdef in newer Unity versions. (#833)
+
 v3.13.0
 ======
 
diff --git a/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef b/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef
new file mode 100644
index 000000000..5cb035b57
--- /dev/null
+++ b/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef
@@ -0,0 +1,17 @@
+{
+    "name": "Fungus.FungusLuaJSONCheckerEditor",
+    "references": [
+        "GUID:007db7f7a4c8f944990d71603a110f82"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ],
+    "excludePlatforms": [],
+    "allowUnsafeCode": false,
+    "overrideReferences": false,
+    "precompiledReferences": [],
+    "autoReferenced": true,
+    "defineConstraints": [],
+    "versionDefines": [],
+    "noEngineReferences": false
+}
\ No newline at end of file
diff --git a/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef.meta b/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef.meta
new file mode 100644
index 000000000..bbb359888
--- /dev/null
+++ b/Assets/Fungus/Thirdparty/FungusLua/Thirdparty/JSON/Editor/Fungus.FungusLuaJSONCheckerEditor.asmdef.meta
@@ -0,0 +1,7 @@
+fileFormatVersion: 2
+guid: 7c368c7d787b2f7418e16e5079276def
+AssemblyDefinitionImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: