diff --git a/src/Dahomey.Cbor/Dahomey.Cbor.csproj b/src/Dahomey.Cbor/Dahomey.Cbor.csproj
index d8d81e9..cf3fd68 100644
--- a/src/Dahomey.Cbor/Dahomey.Cbor.csproj
+++ b/src/Dahomey.Cbor/Dahomey.Cbor.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net9.0</TargetFrameworks>
+	<SuppressTfmSupportBuildWarnings>true</SuppressTfmSupportBuildWarnings>
     <LangVersion>12.0</LangVersion>
     <Nullable>enable</Nullable>
     <PackageReleaseNotes>cf. https://github.com/dahomey-technologies/Dahomey.Cbor/releases/tag/$(Version)</PackageReleaseNotes>
@@ -25,7 +26,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
-    <PackageReference Include="System.Collections.Immutable" Version="7.0.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="9.0.9" />
     <PackageReference Include="Nullable" Version="1.3.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -33,7 +34,7 @@
   </ItemGroup>
 
   <ItemGroup>
-      <PackageReference Include="System.IO.Pipelines" Version="7.0.0" />
+      <PackageReference Include="System.IO.Pipelines" Version="9.0.9" />
   </ItemGroup>
 
 </Project>
diff --git a/src/Dahomey.Cbor/Serialization/CborWriter.cs b/src/Dahomey.Cbor/Serialization/CborWriter.cs
index c6d505e..0cd0893 100644
--- a/src/Dahomey.Cbor/Serialization/CborWriter.cs
+++ b/src/Dahomey.Cbor/Serialization/CborWriter.cs
@@ -201,7 +201,7 @@ public void WriteString(string? value)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void WriteString(ReadOnlySpan<byte> value)
         {
-            if (value == null)
+            if (value.IsEmpty)
             {
                 WriteNull();
                 return;