diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index c2b7a7b..b3242d2 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -4,6 +4,7 @@ on:
   pull_request:
     branches:
       - main
+      - 'release/v*'
 
 concurrency:
   group: ci-pr-${{ github.ref }}-1
diff --git a/Mono.TextTemplating.Tests/AssemblyLoadContextTests.cs b/Mono.TextTemplating.Tests/AssemblyLoadContextTests.cs
index 9ca2997..4b8bb5b 100644
--- a/Mono.TextTemplating.Tests/AssemblyLoadContextTests.cs
+++ b/Mono.TextTemplating.Tests/AssemblyLoadContextTests.cs
@@ -31,6 +31,21 @@ protected override void VerifyFinalState ((SnapshotSet<string> assembliesInDefau
 
 		state.allContexts.AssertUnchanged ();
 	}
+
+	/// Issue #143: System.Text.Json is a framework assembly on .NET Core 3.0 and does not need to be specified by absolute path
+	[Fact]
+	public async Task LoadSystemTextJson ()
+	{
+		string template = "<#@ assembly name=\"System.Text.Json\" #><#=System.Text.Json.JsonValueKind.Array.ToString()#>";
+
+		var gen = new TemplateGenerator ();
+		(_, string content, _) = await gen.ProcessTemplateAsync (null, template, null);
+
+		CompilerError firstError = gen.Errors.OfType<CompilerError> ().FirstOrDefault ();
+		Assert.Null (firstError);
+
+		Assert.Equal ("Array", content);
+	}
 }
 
 #endif
\ No newline at end of file
diff --git a/Mono.TextTemplating.Tests/ProcessingTests.cs b/Mono.TextTemplating.Tests/ProcessingTests.cs
index 4076f3c..344190c 100644
--- a/Mono.TextTemplating.Tests/ProcessingTests.cs
+++ b/Mono.TextTemplating.Tests/ProcessingTests.cs
@@ -117,6 +117,22 @@ public async Task SetLangVersionViaAdditionalArgsInProcess ()
 		}
 #endif
 
+		[Fact]
+		public async Task SetOutputExtension ()
+		{
+			string inputContent = "<#@ output extension=\".cfg\" #>";
+			string inputFile = "hello.tt";
+			string outputName = "hello.txt";
+
+			// this reproduces the calls made by dotnet-t4
+			var gen = new TemplateGenerator ();
+			var pt = gen.ParseTemplate (inputFile, inputContent);
+			TemplateSettings settings = TemplatingEngine.GetSettings (gen, pt);
+			(outputName, _) = await gen.ProcessTemplateAsync (pt, inputFile, inputContent, outputName, settings);
+
+			Assert.Equal ("hello.cfg", outputName);
+		}
+
 		[Fact]
 		public async Task ImportReferencesTest ()
 		{
diff --git a/Mono.TextTemplating/Mono.TextTemplating/TemplateAssemblyLoadContext.cs b/Mono.TextTemplating/Mono.TextTemplating/TemplateAssemblyLoadContext.cs
index 59bb59b..7453e0c 100644
--- a/Mono.TextTemplating/Mono.TextTemplating/TemplateAssemblyLoadContext.cs
+++ b/Mono.TextTemplating/Mono.TextTemplating/TemplateAssemblyLoadContext.cs
@@ -3,6 +3,7 @@
 
 #if FEATURE_ASSEMBLY_LOAD_CONTEXT
 
+using System;
 using System.CodeDom.Compiler;
 using System.IO;
 using System.Reflection;
@@ -52,9 +53,20 @@ protected override Assembly Load (AssemblyName assemblyName)
 				return hostAssembly;
 			}
 
-			foreach (var asmFile in templateAssemblyFiles) {
-				if (assemblyName.Name == Path.GetFileNameWithoutExtension (asmFile)) {
-					return LoadFromAssemblyPath (asmFile);
+			for (int i = 0; i < templateAssemblyFiles.Length; i++) {
+				var asmFile = templateAssemblyFiles[i];
+				if (asmFile is null) {
+					continue;
+				}
+				if (MemoryExtensions.Equals (assemblyName.Name, Path.GetFileNameWithoutExtension (asmFile.AsSpan()), StringComparison.OrdinalIgnoreCase)) {
+					// if the file doesn't exist, fall through to host.ResolveAssemblyReference
+					if (File.Exists (asmFile)) {
+						return LoadFromAssemblyPath (asmFile);
+					} else {
+						// null out the missing file so we don't check it exists again
+						templateAssemblyFiles[i] = null;
+						break;
+					}
 				}
 			}
 
diff --git a/Mono.TextTemplating/Mono.TextTemplating/TemplateGenerator.cs b/Mono.TextTemplating/Mono.TextTemplating/TemplateGenerator.cs
index b92273b..92a8666 100644
--- a/Mono.TextTemplating/Mono.TextTemplating/TemplateGenerator.cs
+++ b/Mono.TextTemplating/Mono.TextTemplating/TemplateGenerator.cs
@@ -268,7 +268,7 @@ public string PreprocessTemplate (
 
 			var outputContent = await Engine.ProcessTemplateAsync (pt, inputContent, settings, this, token).ConfigureAwait (false);
 
-			return (outputFileName, outputContent);
+			return (OutputFile, outputContent);
 		}
 
 		#region Virtual members