diff --git a/src/rime/algo/strings.h b/src/rime/algo/strings.h
index d74357ffd..6cfa1f3bf 100644
--- a/src/rime/algo/strings.h
+++ b/src/rime/algo/strings.h
@@ -120,9 +120,9 @@ string ConcatPieces(std::initializer_list<pair<const char*, std::size_t>> list);
 
 template <typename... Args>
 string concat(const Args&... args) {
-  using namespace details;
+  using namespace ::rime::strings::details;
   return ConcatPieces(
-      {static_cast<const Piece&>(PieceTraits<Args>::forward(args))
+      {static_cast<const Piece&>(details::PieceTraits<Args>::forward(args))
            .ToPair()...});
 }