diff --git a/src/libexpr/paths.cc b/src/libexpr/paths.cc
index e2101858d..56e22a7f6 100644
--- a/src/libexpr/paths.cc
+++ b/src/libexpr/paths.cc
@@ -49,8 +49,7 @@ SourcePath EvalState::decodePath(std::string_view s, PosIdx pos)
 
             SourcePath path {accessor->second, CanonPath(s)};
 
-            static bool warned = false;
-            warnOnce(warned, "applying 'toString' to path '%s' and then accessing it is deprecated, at %s", path, positions[pos]);
+            warn("applying 'toString' to path '%s' and then accessing it is deprecated, at %s", path, positions[pos]);
 
             return path;
         } catch (std::invalid_argument & e) {