diff --git a/spot/tl/expansions.cc b/spot/tl/expansions.cc
index 0896dd6b5..402236ea6 100644
--- a/spot/tl/expansions.cc
+++ b/spot/tl/expansions.cc
@@ -504,13 +504,9 @@ namespace spot
         {
           std::sort(exp.begin(), exp.end(),
                     [](const auto& lhs, const auto& rhs) {
-                         bdd_less_than_stable blt;
-                         // first sort by label, then by suffix
-                         if (blt(lhs.first, rhs.first))
-                           return true;
-                         formula_ptr_less_than_bool_first flt;
-                         return flt(lhs.second, rhs.second);
-                   });
+                         return std::make_pair(lhs.first.id(), lhs.second.id())
+                           < std::make_pair(rhs.first.id(), rhs.second.id());
+                    });
           exp.erase(std::unique(exp.begin(), exp.end()), exp.end());
         }
     }
diff --git a/spot/tl/expansions2.cc b/spot/tl/expansions2.cc
index ecd98f5cb..d80e5ffa3 100644
--- a/spot/tl/expansions2.cc
+++ b/spot/tl/expansions2.cc
@@ -503,13 +503,9 @@ namespace spot
         {
           std::sort(exp.begin(), exp.end(),
                     [](const auto& lhs, const auto& rhs) {
-                         bdd_less_than_stable blt;
-                         // first sort by label, then by suffix
-                         if (blt(lhs.first, rhs.first))
-                           return true;
-                         formula_ptr_less_than_bool_first flt;
-                         return flt(lhs.second, rhs.second);
-                   });
+                         return std::make_pair(lhs.first.id(), lhs.second.id())
+                           < std::make_pair(rhs.first.id(), rhs.second.id());
+                    });
           exp.erase(std::unique(exp.begin(), exp.end()), exp.end());
         }
     }