diff --git a/src/highlight.h b/src/highlight.h
index 6a873f90c..5d904e75a 100644
--- a/src/highlight.h
+++ b/src/highlight.h
@@ -70,14 +70,16 @@ struct highlight_spec_t {
     }
 };
 
+namespace std {
 template <>
-struct std::hash<highlight_spec_t> {
+struct hash<highlight_spec_t> {
     std::size_t operator()(const highlight_spec_t &v) const {
         size_t vals[4] = {static_cast<uint32_t>(v.foreground), static_cast<uint32_t>(v.background),
                           v.valid_path, v.force_underline};
         return (vals[0] << 0) + (vals[1] << 6) + (vals[2] << 12) + (vals[3] << 18);
     }
 };
+}  // namespace std
 
 class history_item_t;
 class operation_context_t;