diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8f6a8c1..69b7c1f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -3,33 +3,33 @@ version: 2.1
 workflows:
   build:
     jobs:
-      - linux-arm64-glibc-net-8:
+      - linux-arm64-glibc-net-9:
           filters:
             tags:
               only: /^v.*/
-      - linux-arm64-musl-net-8:
+      - linux-arm64-musl-net-9:
           filters:
             tags:
               only: /^v.*/
 
 jobs:
-  linux-arm64-glibc-net-8:
+  linux-arm64-glibc-net-9:
     resource_class: arm.medium
     machine:
       image: ubuntu-2204:current
     steps:
       - checkout
       - run: |
-          sudo docker run -dit --name netvips -e CI -v "$(pwd):/mnt/netvips" -w /mnt/netvips mcr.microsoft.com/dotnet/sdk:8.0-bookworm-slim-arm64v8
+          sudo docker run -dit --name netvips -e CI -v "$(pwd):/mnt/netvips" -w /mnt/netvips mcr.microsoft.com/dotnet/sdk:9.0-bookworm-slim-arm64v8
           sudo docker exec netvips sh -c "apt-get update && apt-get install -y fontconfig-config"
       - run: sudo docker exec netvips bash -c "./build.sh"
-  linux-arm64-musl-net-8:
+  linux-arm64-musl-net-9:
     resource_class: arm.medium
     machine:
       image: ubuntu-2204:current
     steps:
       - checkout
       - run: |
-          sudo docker run -dit --name netvips -e CI -v "$(pwd):/mnt/netvips" -w /mnt/netvips mcr.microsoft.com/dotnet/sdk:8.0-alpine3.19-arm64v8
+          sudo docker run -dit --name netvips -e CI -v "$(pwd):/mnt/netvips" -w /mnt/netvips mcr.microsoft.com/dotnet/sdk:9.0-alpine3.20-arm64v8
           sudo docker exec netvips sh -c "apk add bash font-noto --update-cache"
       - run: sudo docker exec netvips bash -c "./build.sh"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index df80cf2..ccf4416 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,13 +9,13 @@ jobs:
       matrix:
         include:
           - os: ubuntu-22.04
-            container: mcr.microsoft.com/dotnet/sdk:8.0-bookworm-slim
+            container: mcr.microsoft.com/dotnet/sdk:9.0-bookworm-slim
             script: ./build.sh
           - os: ubuntu-22.04
             container: rockylinux:8
             script: ./build.sh
           - os: ubuntu-22.04
-            container: mcr.microsoft.com/dotnet/sdk:8.0-alpine3.18
+            container: mcr.microsoft.com/dotnet/sdk:9.0-alpine3.20
             script: ./build.sh
           - os: macos-13
             script: ./build.sh
@@ -29,15 +29,15 @@ jobs:
           apt-get install -y fontconfig-config
       - name: Dependencies (Rocky Linux 8)
         if: contains(matrix.container, 'rockylinux')
-        run: dnf install -y dotnet-sdk-8.0 google-noto-sans-fonts which
-      - name: Dependencies (Alpine 3.18)
+        run: dnf install -y dotnet-sdk-9.0 google-noto-sans-fonts which
+      - name: Dependencies (Alpine 3.20)
         if: contains(matrix.container, 'alpine')
         run: apk add bash font-noto --update-cache
       - name: Setup dotnet (macOS 13, Windows 2022)
         if: runner.os != 'Linux'
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: 8.x
+          dotnet-version: 9.x
       - name: Checkout
         uses: actions/checkout@v4
       - name: Test
diff --git a/Dockerfile b/Dockerfile
index ab4ec6c..fd4cf8d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM mcr.microsoft.com/dotnet/sdk:8.0-alpine AS build
+FROM mcr.microsoft.com/dotnet/sdk:9.0-alpine AS build
 LABEL maintainer="Kleis Auke Wolthuizen <info@kleisauke.nl>"
 
 RUN apk add bash font-noto --update-cache
diff --git a/NetVips.sln b/NetVips.sln
index ec18956..bb3bc6c 100644
--- a/NetVips.sln
+++ b/NetVips.sln
@@ -1,6 +1,6 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
-VisualStudioVersion = 17.8.34309.116
+VisualStudioVersion = 17.12.35506.116 d17.12
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NetVips", "src\NetVips\NetVips.csproj", "{5BCB7929-52B1-459B-89E5-7C2059850C60}"
 EndProject
diff --git a/build/NetVips.Build.csproj b/build/NetVips.Build.csproj
index f52af6c..765bf6e 100644
--- a/build/NetVips.Build.csproj
+++ b/build/NetVips.Build.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <RootNamespace></RootNamespace>
     <IsPackable>False</IsPackable>
@@ -19,6 +19,8 @@
     </PackageReference>
     <PackageReference Include="Nuke.Common" Version="8.1.4" />
     <PackageReference Include="SharpZipLib" Version="1.4.2" />
+    <!-- https://github.com/nuke-build/nuke/issues/818 -->
+    <PackageReference Include="System.Runtime.Serialization.Formatters" Version="9.0.0" />
   </ItemGroup>
 
 </Project>
diff --git a/docker.sh b/docker.sh
index 9062870..de6af7c 100755
--- a/docker.sh
+++ b/docker.sh
@@ -6,7 +6,7 @@ if ! [ -x "$(command -v docker)" ]; then
 fi
 
 # Ensure latest .NET SDK
-docker pull mcr.microsoft.com/dotnet/sdk:8.0-alpine
+docker pull mcr.microsoft.com/dotnet/sdk:9.0-alpine
 
 # Create a machine image with all the required build tools pre-installed
 docker build . -t netvips
diff --git a/docs/NetVips.Docs.csproj b/docs/NetVips.Docs.csproj
index d281719..0b2b593 100644
--- a/docs/NetVips.Docs.csproj
+++ b/docs/NetVips.Docs.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Platforms>x64;x86;ARM64;ARM32</Platforms>
     <OutputType>Exe</OutputType>
     <AppendRuntimeIdentifierToOutputPath>false</AppendRuntimeIdentifierToOutputPath>
diff --git a/samples/NetVips.Samples/NetVips.Samples.csproj b/samples/NetVips.Samples/NetVips.Samples.csproj
index 8ba4a07..02624f2 100644
--- a/samples/NetVips.Samples/NetVips.Samples.csproj
+++ b/samples/NetVips.Samples/NetVips.Samples.csproj
@@ -3,7 +3,7 @@
   <Import Project="..\..\build\common.props" />
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <OutputType>Exe</OutputType>
     <RootNamespace>NetVips</RootNamespace>
     <Optimize>true</Optimize>
@@ -15,7 +15,7 @@
     <ProjectReference Include="..\..\src\NetVips.Extensions\NetVips.Extensions.csproj" />
   </ItemGroup>
 
-  <!-- System.Drawing.Common 8.0.0 is only supported on Windows -->
+  <!-- System.Drawing.Common 6+ is Windows-only -->
   <ItemGroup Condition="!$([MSBuild]::IsOSPlatform('Windows'))">
     <Compile Remove="Samples/GdiConvert.cs" />
   </ItemGroup>
diff --git a/src/NetVips.Extensions/NetVips.Extensions.csproj b/src/NetVips.Extensions/NetVips.Extensions.csproj
index 77bfb5a..8d4f4ac 100644
--- a/src/NetVips.Extensions/NetVips.Extensions.csproj
+++ b/src/NetVips.Extensions/NetVips.Extensions.csproj
@@ -21,7 +21,10 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETFramework'">
-    <PackageReference Include="System.Drawing.Common" Version="8.0.10" />
+    <!-- Constrain the version to 8.0.11, as later versions require .NET 8.0.
+         https://github.com/dotnet/winforms/issues/9851
+    -->
+    <PackageReference Include="System.Drawing.Common" Version="[8.0.11]" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
diff --git a/src/NetVips/NetVips.csproj b/src/NetVips/NetVips.csproj
index 1a46cd0..b60bf4f 100644
--- a/src/NetVips/NetVips.csproj
+++ b/src/NetVips/NetVips.csproj
@@ -23,7 +23,10 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
-    <PackageReference Include="System.Buffers" Version="4.5.1" />
+    <!-- Constrain the version to 4.5.1, as later versions require .NET Framework 4.6.2.
+         https://github.com/dotnet/maintenance-packages/issues/42
+    -->
+    <PackageReference Include="System.Buffers" Version="[4.5.1]" />
   </ItemGroup>
 
 </Project>
\ No newline at end of file
diff --git a/tests/NetVips.Benchmarks/Config.cs b/tests/NetVips.Benchmarks/Config.cs
index e19f96a..60567e0 100644
--- a/tests/NetVips.Benchmarks/Config.cs
+++ b/tests/NetVips.Benchmarks/Config.cs
@@ -14,17 +14,14 @@ public Config()
         // Only support LTS and latest releases
         // https://endoflife.date/dotnet
         AddJob(Job.Default
-#if NET6_0
-                .WithToolchain(CsProjCoreToolchain.NetCoreApp60)
-                .WithId(".NET 6.0 CLI")
-#elif NET7_0
-                .WithToolchain(CsProjCoreToolchain.NetCoreApp70)
-                .WithRuntime(NativeAotRuntime.Net70)
-                .WithId(".NET 7.0 CLI (NativeAOT)")
-#elif NET8_0
+#if NET8_0
                 .WithToolchain(CsProjCoreToolchain.NetCoreApp80)
                 .WithRuntime(NativeAotRuntime.Net80)
                 .WithId(".NET 8.0 CLI (NativeAOT)")
+#elif NET9_0
+                .WithToolchain(CsProjCoreToolchain.NetCoreApp90)
+                .WithRuntime(NativeAotRuntime.Net90)
+                .WithId(".NET 9.0 CLI (NativeAOT)")
 #endif
 #if GLOBAL_VIPS
                 .WithArguments(new Argument[]
diff --git a/tests/NetVips.Benchmarks/NetVips.Benchmarks.csproj b/tests/NetVips.Benchmarks/NetVips.Benchmarks.csproj
index 77141f3..7e2b881 100644
--- a/tests/NetVips.Benchmarks/NetVips.Benchmarks.csproj
+++ b/tests/NetVips.Benchmarks/NetVips.Benchmarks.csproj
@@ -3,7 +3,7 @@
   <Import Project="..\..\build\common.props" />
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <OutputType>Exe</OutputType>
     <Optimize>true</Optimize>
     <Platforms>x64;x86;ARM64;ARM32</Platforms>
@@ -23,7 +23,7 @@
     <PackageReference Include="SixLabors.ImageSharp" Version="3.1.5" />
     <PackageReference Include="SkiaSharp" Version="2.88.8" />
     <PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="2.88.8" Condition="$([MSBuild]::IsOSPlatform('Linux'))" />
-    <PackageReference Include="System.Drawing.Common" Version="8.0.10" Condition="$([MSBuild]::IsOSPlatform('Windows'))" />
+    <PackageReference Include="System.Drawing.Common" Version="9.0.0" Condition="$([MSBuild]::IsOSPlatform('Windows'))" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/tests/NetVips.Tests/NetVips.Tests.csproj b/tests/NetVips.Tests/NetVips.Tests.csproj
index 5c21386..0aea841 100644
--- a/tests/NetVips.Tests/NetVips.Tests.csproj
+++ b/tests/NetVips.Tests/NetVips.Tests.csproj
@@ -3,7 +3,7 @@
   <Import Project="..\..\build\common.props" />
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <IsPackable>false</IsPackable>
     <OutputType>Library</OutputType>
     <Platforms>x64;x86;ARM64;ARM32</Platforms>