diff --git a/src/libmain/progress-bar.cc b/src/libmain/progress-bar.cc
index 63955eed1..f4306ab91 100644
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@@ -11,7 +11,7 @@
 
 namespace nix {
 
-static std::string getS(const std::vector<Logger::Field> & fields, size_t n)
+static std::string_view getS(const std::vector<Logger::Field> & fields, size_t n)
 {
     assert(n < fields.size());
     assert(fields[n].type == Logger::Field::tString);