diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index f4e846d4..61451414 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -28,6 +28,7 @@ jobs:
           6.x
           7.x
           8.x
+          9.x
 
     - name: Log dotnet info
       run: dotnet --info
@@ -47,7 +48,7 @@ jobs:
     - name: Setup dotnet
       uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: '8.x'
+        dotnet-version: '9.x'
     
     - name: Make repo pushable
       env:
diff --git a/.github/workflows/publish_release.yml b/.github/workflows/publish_release.yml
index e7e62be3..847902e2 100644
--- a/.github/workflows/publish_release.yml
+++ b/.github/workflows/publish_release.yml
@@ -25,7 +25,7 @@ jobs:
     - name: Setup dotnet
       uses: actions/setup-dotnet@v4
       with: 
-        dotnet-version: '8.x'
+        dotnet-version: '9.x'
 
     - name: Get Version
       id: get_version
diff --git a/Directory.Build.props b/Directory.Build.props
index d21acaae..c965981d 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -4,7 +4,7 @@
 		<HarmonyXVersion>2.13.0</HarmonyXVersion>
 		<HarmonyXVersionFull>2.13.0.0</HarmonyXVersionFull>
 		<HarmonyXVersionSuffix></HarmonyXVersionSuffix>
-		<MonoModRuntimeDetour>25.1.2</MonoModRuntimeDetour>
+		<MonoModRuntimeDetour>25.2.2</MonoModRuntimeDetour>
 	</PropertyGroup>
 
 </Project>
diff --git a/Harmony/Internal/Util/EmitterExtensions.cs b/Harmony/Internal/Util/EmitterExtensions.cs
index 83f24843..ff3e9686 100644
--- a/Harmony/Internal/Util/EmitterExtensions.cs
+++ b/Harmony/Internal/Util/EmitterExtensions.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
@@ -198,13 +198,18 @@ public static LocalBuilder GetLocal(this CecilILGenerator il, VariableDefinition
             return loc;
         }
 
+        // https://github.com/MonoMod/MonoMod/commit/2011243901351e69b6b5da89631e01bc8eb61da5
+        // https://github.com/dotnet/runtime/blob/f1332ab0d82ee0e21ca387cbd1c8a87c5dfa4906/src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/RuntimeLocalBuilder.cs
+        // In .NET 9, LocalBuilder is an abstract type, so we look for RuntimeLocalBuilder first.
+        private static readonly Type t_LocalBuilder =
+            Type.GetType("System.Reflection.Emit.RuntimeLocalBuilder") ?? typeof(LocalBuilder);
         private static readonly ConstructorInfo c_LocalBuilder =
-            typeof(LocalBuilder).GetConstructors(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance)
+            t_LocalBuilder.GetConstructors(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance)
                                 .OrderByDescending(c => c.GetParameters().Length).First();
         private static readonly FieldInfo f_LocalBuilder_position =
-            typeof(LocalBuilder).GetField("position", BindingFlags.NonPublic | BindingFlags.Instance);
+            t_LocalBuilder.GetField("position", BindingFlags.NonPublic | BindingFlags.Instance);
         private static readonly FieldInfo f_LocalBuilder_is_pinned =
-            typeof(LocalBuilder).GetField("is_pinned", BindingFlags.NonPublic | BindingFlags.Instance);
+            t_LocalBuilder.GetField("is_pinned", BindingFlags.NonPublic | BindingFlags.Instance);
         private static int c_LocalBuilder_params = c_LocalBuilder.GetParameters().Length;
     }
 }
diff --git a/HarmonyTests/HarmonyTests.csproj b/HarmonyTests/HarmonyTests.csproj
index c9c8065a..57c94e89 100644
--- a/HarmonyTests/HarmonyTests.csproj
+++ b/HarmonyTests/HarmonyTests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>net35;net452;net48;netcoreapp3.1;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+        <TargetFrameworks>net35;net452;net48;netcoreapp3.1;net5.0;net6.0;net7.0;net8.0;net9.0</TargetFrameworks>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <LangVersion>latest</LangVersion>
         <IsPackable>false</IsPackable>
@@ -32,7 +32,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
         <PackageReference Include="NUnit" Version="3.14.0" />
         <PackageReference Include="NUnit3TestAdapter" Version="4.3.2">
             <PrivateAssets>all</PrivateAssets>
@@ -50,7 +50,7 @@
 <!--    </ItemGroup>-->
 
     <ItemGroup Condition="'$(TargetFrameworkIdentifier)'=='.NETCoreApp'">
-        <PackageReference Include="Lokad.ILPack" Version="0.1.7" PrivateAssets="all" />
+        <PackageReference Include="Lokad.ILPack" Version="0.2.0" PrivateAssets="all" />
     </ItemGroup>
 
 </Project>