diff --git a/src/plugins/wp/Why3Import.ml b/src/plugins/wp/Why3Import.ml
index 7ee024fab109579b7bcb0326bc037851c11e3bb4..d48607a55be557016f0198ba8cb2660ad69ed11a 100644
--- a/src/plugins/wp/Why3Import.ml
+++ b/src/plugins/wp/Why3Import.ml
@@ -52,7 +52,7 @@ let open_theory (env) (theories) =
          W.Pretty.print_theory Format.std_formatter theory;
 
        with W.Env.LibraryNotFound paths ->
-             L.debug ~level:0 "Library not found at %s " (String.concat "." paths);
+             L.debug ~level:0 "Library %s not found at %s " thy_n (String.concat "." paths);
     ) (extract_last_segments theories)