diff --git a/UnitsNet.Benchmark/UnitsNet.Benchmark.csproj b/UnitsNet.Benchmark/UnitsNet.Benchmark.csproj
index a8e9e2d59b..cd95d63f0d 100644
--- a/UnitsNet.Benchmark/UnitsNet.Benchmark.csproj
+++ b/UnitsNet.Benchmark/UnitsNet.Benchmark.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <Version>4.0.0.0</Version>
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <AssemblyTitle>UnitsNet.Benchmark</AssemblyTitle>
diff --git a/UnitsNet.NumberExtensions.Tests/UnitsNet.NumberExtensions.Tests.csproj b/UnitsNet.NumberExtensions.Tests/UnitsNet.NumberExtensions.Tests.csproj
index cbf788c569..95e55dfba7 100644
--- a/UnitsNet.NumberExtensions.Tests/UnitsNet.NumberExtensions.Tests.csproj
+++ b/UnitsNet.NumberExtensions.Tests/UnitsNet.NumberExtensions.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net48;net8.0</TargetFrameworks>
+    <TargetFrameworks>net48;net8.0;net9.0</TargetFrameworks>
     <RootNamespace>UnitsNet.NumberExtensions.Tests</RootNamespace>
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
diff --git a/UnitsNet.NumberExtensions/UnitsNet.NumberExtensions.csproj b/UnitsNet.NumberExtensions/UnitsNet.NumberExtensions.csproj
index 48bc36dbff..d4506ebd9d 100644
--- a/UnitsNet.NumberExtensions/UnitsNet.NumberExtensions.csproj
+++ b/UnitsNet.NumberExtensions/UnitsNet.NumberExtensions.csproj
@@ -22,7 +22,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <RootNamespace>UnitsNet</RootNamespace>
-    <TargetFrameworks>netstandard2.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/UnitsNet.Serialization.JsonNet.Tests/UnitsNet.Serialization.JsonNet.Tests.csproj b/UnitsNet.Serialization.JsonNet.Tests/UnitsNet.Serialization.JsonNet.Tests.csproj
index 6935d540ce..b50af19181 100644
--- a/UnitsNet.Serialization.JsonNet.Tests/UnitsNet.Serialization.JsonNet.Tests.csproj
+++ b/UnitsNet.Serialization.JsonNet.Tests/UnitsNet.Serialization.JsonNet.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <RootNamespace>UnitsNet.Serialization.JsonNet.Tests</RootNamespace>
     <IsTestProject>true</IsTestProject>
     <NoWarn>CS0618</NoWarn>
diff --git a/UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.csproj b/UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.csproj
index e76f21b118..ba3fa99a4f 100644
--- a/UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.csproj
+++ b/UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.csproj
@@ -24,7 +24,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <RootNamespace>UnitsNet.Serialization.JsonNet</RootNamespace>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <!-- Strong name signing -->
diff --git a/UnitsNet.Serialization.JsonNet/UnitsNetBaseJsonConverter.cs b/UnitsNet.Serialization.JsonNet/UnitsNetBaseJsonConverter.cs
index 6e9d2940bd..bd4d213012 100644
--- a/UnitsNet.Serialization.JsonNet/UnitsNetBaseJsonConverter.cs
+++ b/UnitsNet.Serialization.JsonNet/UnitsNetBaseJsonConverter.cs
@@ -92,7 +92,7 @@ protected IQuantity ConvertValueUnit(ValueUnit valueUnit)
 
             if (registeredQuantity is not null)
             {
-                return (IQuantity)Activator.CreateInstance(registeredQuantity, valueUnit.Value, unit);
+                return (IQuantity)Activator.CreateInstance(registeredQuantity, valueUnit.Value, unit)!;
             }
 
             return Quantity.From(valueUnit.Value, unit);
diff --git a/UnitsNet.Tests/UnitsNet.Tests.csproj b/UnitsNet.Tests/UnitsNet.Tests.csproj
index 9fa6a20cc9..d23783c60f 100644
--- a/UnitsNet.Tests/UnitsNet.Tests.csproj
+++ b/UnitsNet.Tests/UnitsNet.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <IsTestProject>true</IsTestProject>
     <NoWarn>CS0618</NoWarn><!-- CS0618: 'member' is obsolete: 'text' (we often obsolete things before removal) -->
diff --git a/UnitsNet/UnitsNet.csproj b/UnitsNet/UnitsNet.csproj
index 7b43b040f5..186c8a04d8 100644
--- a/UnitsNet/UnitsNet.csproj
+++ b/UnitsNet/UnitsNet.csproj
@@ -24,7 +24,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <RootNamespace>UnitsNet</RootNamespace>
-    <TargetFrameworks>netstandard2.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net8.0;net9.0</TargetFrameworks>
   </PropertyGroup>
 
   <!-- Strong name signing -->