diff --git a/spot/twaalgos/toparity.cc b/spot/twaalgos/toparity.cc
index 31d7b190b..0b46e6224 100644
--- a/spot/twaalgos/toparity.cc
+++ b/spot/twaalgos/toparity.cc
@@ -1583,7 +1583,8 @@ run()
         if (options.propagate_col)
         {
             propagate_marks_here(sub_automaton);
-            propagate_marks_here(deg);
+            if (deg != sub_automaton)
+              propagate_marks_here(deg);
         }
 
         std::map<unsigned, car_state> state2car_sub, state2car_deg;
diff --git a/spot/twaalgos/toparity.hh b/spot/twaalgos/toparity.hh
index 3c935f095..7d2701581 100644
--- a/spot/twaalgos/toparity.hh
+++ b/spot/twaalgos/toparity.hh
@@ -49,7 +49,7 @@ namespace spot
     /// get a better result if we don't apply partial_degeneralize.
     bool force_degen = true;
     /// If \c scc_acc_clean is true, to_parity() will ignore colors
-    /// no occoring in an SCC while processing this SCC.
+    /// not occurring in an SCC while processing this SCC.
     bool acc_clean = true;
     /// If \c parity_equiv is true, to_parity() will check if there
     /// exists a permutations of colors such that the acceptance