diff --git a/Primary/Api.cs b/Primary/Api.cs
index 8a804ed..a92caad 100644
--- a/Primary/Api.cs
+++ b/Primary/Api.cs
@@ -30,7 +30,14 @@ public class Api
         public Api(Uri baseUri, HttpClient httpClient = null)
         {
             BaseUri = baseUri;
-            HttpClient = httpClient ?? new HttpClient() { DefaultRequestVersion = new(2, 0) };
+            HttpClient = httpClient ?? new HttpClient()
+            {
+#if NET6
+                DefaultRequestVersion = new(2, 0) 
+#else
+#warning Not using HTTP/2.
+#endif
+            };
         }
 
         public Uri BaseUri { get; private set; }
diff --git a/Primary/Primary.csproj b/Primary/Primary.csproj
index b058568..7bd348c 100644
--- a/Primary/Primary.csproj
+++ b/Primary/Primary.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <Version>0.10.0-beta</Version>
     <PackageId>Primary.Net</PackageId>