diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 6b8ec4279bb30..6c0646ce78943 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -10607,6 +10607,9 @@ AccessorDecl *AccessorDecl::createParsed(
       // The cloned parameter is implicit.
       param->setImplicit();
 
+      if (subscriptParam->isSending())
+        param->setSending();
+
       newParams.push_back(param);
     }
   }
diff --git a/test/Concurrency/sending_witness_subscript.swift b/test/Concurrency/sending_witness_subscript.swift
new file mode 100644
index 0000000000000..b9d55791fe3a2
--- /dev/null
+++ b/test/Concurrency/sending_witness_subscript.swift
@@ -0,0 +1,11 @@
+// RUN: %target-swift-frontend -emit-sil -swift-version 6 %s -o /dev/null -verify
+
+class NonSendableKlass {}
+
+protocol P {
+  subscript(_: sending NonSendableKlass) -> sending NonSendableKlass { get }
+}
+
+struct S: P {
+  subscript(_: sending NonSendableKlass) -> sending NonSendableKlass { NonSendableKlass() }
+}