diff --git a/clang/test/OpenMP/for_reduction_codegen_UDR.cpp b/clang/test/OpenMP/for_reduction_codegen_UDR.cpp
index f3816de5f5bf..6d8223c724f5 100644
--- a/clang/test/OpenMP/for_reduction_codegen_UDR.cpp
+++ b/clang/test/OpenMP/for_reduction_codegen_UDR.cpp
@@ -38,6 +38,7 @@ struct S : public BaseS, public BaseS1 {
   T f;
   S(T a) : f(a + g) {}
   S() : f(g) {}
+  S& operator=(const S&);
   ~S() {}
 };
 void red(BaseS1&, const BaseS1&);