diff --git a/src/Common/Polyfills/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs b/src/Common/Polyfills/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs
index 515ef63c7..244f0875e 100644
--- a/src/Common/Polyfills/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs
+++ b/src/Common/Polyfills/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs
@@ -12,7 +12,7 @@
 namespace System.Runtime.CompilerServices
 {
     /// <summary>Provides a handler used by the language compiler to process interpolated strings into <see cref="string"/> instances.</summary>
-    public ref struct DefaultInterpolatedStringHandler
+    internal ref struct DefaultInterpolatedStringHandler
     {
         // Implementation note:
         // As this type lives in CompilerServices and is only intended to be targeted by the compiler,