diff --git a/Aetheria.Shared/Aetheria.Shared.csproj b/Aetheria.Shared/Aetheria.Shared.csproj
index b546290bd..d67dba1e4 100644
--- a/Aetheria.Shared/Aetheria.Shared.csproj
+++ b/Aetheria.Shared/Aetheria.Shared.csproj
@@ -15,8 +15,6 @@
     <!-- Existing code warnings; the build is a Unity-independence check, not a lint pass -->
     <NoWarn>$(NoWarn);CS0108;CS0114;CS0162;CS0168;CS0169;CS0219;CS0414;CS0618;CS0649;CS8321;CS8981;SYSLIB0021</NoWarn>
     <Assets>$(MSBuildThisFileDirectory)..\Assets\</Assets>
-    <!-- Unity.Mathematics ships only as a Unity package; its sources come from the package cache Unity resolved -->
-    <MathematicsSource>$(MSBuildThisFileDirectory)..\Library\PackageCache\com.unity.mathematics@*\Unity.Mathematics\</MathematicsSource>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(Assets)Scripts\ServerShared\**\*.cs" />
@@ -25,9 +23,9 @@
     <!-- The reactive collections live in UniRx's Unity bridge but fence their Unity parts behind UniRxLibrary -->
     <Compile Include="$(Assets)Plugins\UniRx\Scripts\UnityEngineBridge\ReactiveProperty.cs;$(Assets)Plugins\UniRx\Scripts\UnityEngineBridge\ReactiveCollection.cs;$(Assets)Plugins\UniRx\Scripts\UnityEngineBridge\ReactiveDictionary.cs" />
     <Compile Include="$(Assets)Plugins\Ink\**\*.cs" />
-    <Compile Include="$(MathematicsSource)**\*.cs" Exclude="$(MathematicsSource)math_unity_conversion.cs;$(MathematicsSource)PropertyAttributes.cs" />
   </ItemGroup>
   <ItemGroup>
+    <ProjectReference Include="$(CultLibRoot)\packages\cultmath\src\CultMath\CultMath.csproj" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <!-- Bundled by Unity; .NET Standard 2.1 lacks it -->
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="6.0.0" />
diff --git a/Assets/Scripts/ServerShared/Aetheria.Shared.Unity.asmdef b/Assets/Scripts/ServerShared/Aetheria.Shared.Unity.asmdef
index 49ff6cf33..e86a97903 100644
--- a/Assets/Scripts/ServerShared/Aetheria.Shared.Unity.asmdef
+++ b/Assets/Scripts/ServerShared/Aetheria.Shared.Unity.asmdef
@@ -3,7 +3,6 @@
     "rootNamespace": "",
     "references": [
         "MessagePack",
-        "Unity.Mathematics",
         "UniRx",
         "Ink"
     ],
diff --git a/Assets/Scripts/Tests/Tests.asmdef b/Assets/Scripts/Tests/Tests.asmdef
index ede58b507..dc82ff3de 100644
--- a/Assets/Scripts/Tests/Tests.asmdef
+++ b/Assets/Scripts/Tests/Tests.asmdef
@@ -4,7 +4,6 @@
     "references": [
         "UnityEngine.TestRunner",
         "UnityEditor.TestRunner",
-        "Unity.Mathematics",
         "Aetheria.Shared.Unity"
     ],
     "includePlatforms": [
@@ -14,7 +13,8 @@
     "allowUnsafeCode": false,
     "overrideReferences": true,
     "precompiledReferences": [
-        "nunit.framework.dll"
+        "nunit.framework.dll",
+        "CultMath.dll"
     ],
     "autoReferenced": false,
     "defineConstraints": [
diff --git a/Packages/manifest.json b/Packages/manifest.json
index 456094c0a..2b9bf1f6b 100644
--- a/Packages/manifest.json
+++ b/Packages/manifest.json
@@ -9,7 +9,6 @@
     "com.unity.ide.visualstudio": "2.0.26",
     "com.unity.inputsystem": "1.20.0",
     "com.unity.localization": "1.5.8",
-    "com.unity.mathematics": "1.3.3",
     "com.unity.multiplayer.center": "1.0.1",
     "com.unity.postprocessing": "3.5.4",
     "com.unity.recorder": "5.1.7",
@@ -50,6 +49,7 @@
     "com.unity.modules.video": "1.0.0",
     "com.unity.modules.vr": "1.0.0",
     "com.unity.modules.wind": "1.0.0",
-    "com.unity.modules.xr": "1.0.0"
+    "com.unity.modules.xr": "1.0.0",
+    "org.gamecult.cultmath": "https://github.com/GameCult/CultLib.git?path=/packages/cultmath/unity/org.gamecult.cultmath#cultmath-unity-v0.2.1"
   }
 }