diff --git a/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/PublicAPI.Unshipped.txt b/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/PublicAPI.Unshipped.txt
index 668589bf7..418cff082 100644
--- a/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/PublicAPI.Unshipped.txt
+++ b/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/PublicAPI.Unshipped.txt
@@ -225,6 +225,7 @@ Microsoft.CodeAnalysis.Testing.SourceFileCollection
 Microsoft.CodeAnalysis.Testing.SourceFileCollection.Add((System.Type sourceGeneratorType, string filename, Microsoft.CodeAnalysis.Text.SourceText content) file) -> void
 Microsoft.CodeAnalysis.Testing.SourceFileCollection.Add((System.Type sourceGeneratorType, string filename, string content) file) -> void
 Microsoft.CodeAnalysis.Testing.SourceFileCollection.Add((string filename, string content) file) -> void
+Microsoft.CodeAnalysis.Testing.SourceFileCollection.Add((string filename, string content, System.Text.Encoding encoding) file) -> void
 Microsoft.CodeAnalysis.Testing.SourceFileCollection.SourceFileCollection() -> void
 Microsoft.CodeAnalysis.Testing.SourceFileList
 Microsoft.CodeAnalysis.Testing.SourceFileList.Add(Microsoft.CodeAnalysis.Text.SourceText content) -> void
diff --git a/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/SourceFileCollection.cs b/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/SourceFileCollection.cs
index a4d69e536..8d721b0d1 100644
--- a/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/SourceFileCollection.cs
+++ b/src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.Analyzer.Testing/SourceFileCollection.cs
@@ -18,6 +18,11 @@ public void Add((string filename, string content) file)
             Add((file.filename, SourceText.From(file.content)));
         }
 
+        public void Add((string filename, string content, Encoding encoding) file)
+        {
+            Add((file.filename, SourceText.From(file.content, file.encoding)));
+        }
+
         public void Add((Type sourceGeneratorType, string filename, string content) file)
         {
             var contentWithEncoding = SourceText.From(file.content, Encoding.UTF8);