diff --git a/src/DotRecast.Core/DotRecast.Core.csproj b/src/DotRecast.Core/DotRecast.Core.csproj
index eff52c8..d727bda 100644
--- a/src/DotRecast.Core/DotRecast.Core.csproj
+++ b/src/DotRecast.Core/DotRecast.Core.csproj
@@ -4,8 +4,5 @@
         <TargetFramework>netstandard2.1</TargetFramework>
     </PropertyGroup>
 
-    <ItemGroup>
-        <PackageReference Include="System.Text.Json" Version="7.0.3" />
-    </ItemGroup>
 
 </Project>
diff --git a/src/DotRecast.Detour.Extras/DotRecast.Detour.Extras.csproj b/src/DotRecast.Detour.Extras/DotRecast.Detour.Extras.csproj
index 2a71f47..6b37247 100644
--- a/src/DotRecast.Detour.Extras/DotRecast.Detour.Extras.csproj
+++ b/src/DotRecast.Detour.Extras/DotRecast.Detour.Extras.csproj
@@ -9,4 +9,8 @@
         <ProjectReference Include="..\DotRecast.Detour\DotRecast.Detour.csproj" />
     </ItemGroup>
 
+    <ItemGroup>
+        <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+    </ItemGroup>
+
 </Project>
diff --git a/src/DotRecast.Detour.Extras/Unity/Astar/GraphMetaReader.cs b/src/DotRecast.Detour.Extras/Unity/Astar/GraphMetaReader.cs
index 3ce4207..ce39281 100644
--- a/src/DotRecast.Detour.Extras/Unity/Astar/GraphMetaReader.cs
+++ b/src/DotRecast.Detour.Extras/Unity/Astar/GraphMetaReader.cs
@@ -18,7 +18,7 @@ freely, subject to the following restrictions:
 
 using System.IO;
 using System.IO.Compression;
-using System.Text.Json;
+using Newtonsoft.Json;
 
 namespace DotRecast.Detour.Extras.Unity.Astar
 {
@@ -29,13 +29,13 @@ namespace DotRecast.Detour.Extras.Unity.Astar
             ZipArchiveEntry entry = file.GetEntry(filename);
             using StreamReader reader = new StreamReader(entry.Open());
 
-            JsonSerializerOptions options = new JsonSerializerOptions
-            {
-                PropertyNamingPolicy = JsonNamingPolicy.CamelCase
-            };
-
+            // for unity3d
             var json = reader.ReadToEnd();
-            return JsonSerializer.Deserialize<GraphMeta>(json, options);
+            return JsonConvert.DeserializeObject<GraphMeta>(json);
+            
+            // var settings = new JsonSerializerSettings();
+            // settings.ContractResolver = new CamelCasePropertyNamesContractResolver();
+            //return JsonConvert.DeserializeObject<GraphMeta>(json, settings);
         }
     }
 }
\ No newline at end of file
diff --git a/src/DotRecast.Detour.Extras/Unity/Astar/MetaReader.cs b/src/DotRecast.Detour.Extras/Unity/Astar/MetaReader.cs
index 6ea88ea..686e7b7 100644
--- a/src/DotRecast.Detour.Extras/Unity/Astar/MetaReader.cs
+++ b/src/DotRecast.Detour.Extras/Unity/Astar/MetaReader.cs
@@ -19,9 +19,9 @@ freely, subject to the following restrictions:
 using System;
 using System.IO;
 using System.IO.Compression;
-using System.Text.Json;
-using System.Text.Json.Nodes;
+
 using System.Text.RegularExpressions;
+using Newtonsoft.Json;
 
 namespace DotRecast.Detour.Extras.Unity.Astar
 {
@@ -41,7 +41,7 @@ namespace DotRecast.Detour.Extras.Unity.Astar
             var regex = new Regex(pattern);
             json = regex.Replace(json, replacement);
 
-            var meta = JsonSerializer.Deserialize<Meta>(json);
+            var meta = JsonConvert.DeserializeObject<Meta>(json);
             if (!meta.IsSupportedType())
             {
                 throw new ArgumentException("Unsupported graph type " + string.Join(", ", meta.typeNames));