diff --git a/hphp/hack/hhi/implicit_context.hhi b/hphp/hack/hhi/implicit_context.hhi
index 4946fa70cc4ec2..a0a9d49197908c 100644
--- a/hphp/hack/hhi/implicit_context.hhi
+++ b/hphp/hack/hhi/implicit_context.hhi
@@ -48,7 +48,8 @@ namespace HH {
     )[this::CRun, ctx $f]: Tout;
   }
 
-  <<__Sealed(FBMemoSensitiveImplicitContext::class)>>
+  // Avoid referencing an internal class in OSS.
+  <<__Sealed(FBMemoAgnosticImplicitContext::class)>> // @oss-disable
   abstract class MemoSensitiveImplicitContext extends ImplicitContextBase {
     abstract const type TData as IPureMemoizeParam;