diff --git a/spot/twaalgos/translate_aa.cc b/spot/twaalgos/translate_aa.cc
index 095f92c5a..15633b4ec 100644
--- a/spot/twaalgos/translate_aa.cc
+++ b/spot/twaalgos/translate_aa.cc
@@ -529,12 +529,12 @@ namespace spot
           pref = 0;
         else if (!strcasecmp(version, "derive"))
           pref = 1;
-        else if (!strcasecmp(version, "expansion"))
+        else if (!strcasecmp(version, "lf"))
           pref = 2;
         else
           {
             const char* err = ("sere_aa_translation_options(): argument"
-                              " should be one of {bdd,derive,expansion}");
+                              " should be one of {bdd,derive,lf}");
             if (env)
               err = "SPOT_SERE_AA_TRANSLATE_OPT should be one of {bdd,derive,expansion}";
             throw std::runtime_error(err);