diff --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp
index aac43e2cad603..b0c28531fe873 100644
--- a/clang/lib/Sema/SemaCast.cpp
+++ b/clang/lib/Sema/SemaCast.cpp
@@ -500,7 +500,7 @@ static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
 
   case OR_Deleted: {
     OverloadCandidateSet::iterator Best;
-    OverloadingResult Res =
+    [[maybe_unused]] OverloadingResult Res =
         candidates.BestViableFunction(S, range.getBegin(), Best);
     assert(Res == OR_Deleted && "Inconsistent overload resolution");