diff --git a/spot/tl/expansions2.cc b/spot/tl/expansions2.cc
index d80e5ffa3..c40298d7f 100644
--- a/spot/tl/expansions2.cc
+++ b/spot/tl/expansions2.cc
@@ -540,7 +540,7 @@ namespace spot
         return {{f_bdd, formula::eword()}};
       }
 
-    auto rec = [&d, owner, opts, seen](formula f){
+    auto rec = [&d, owner, seen](formula f){
       return expansion2(f, d, owner, exp_opts::None, seen);
     };
 
@@ -711,7 +711,10 @@ namespace spot
                         if ((li & kj) != bddfalse)
                           res.push_back({li & kj, fj});
                   }
-                res.push_back({li, formula::Fusion({ei, F})});
+
+                formula ei_fusion_F = formula::Fusion({ei, F});
+                if (!ei_fusion_F.is(op::ff))
+                  res.push_back({li, ei_fusion_F});
               }
 
             finalize(res, opts, d, seen);