diff --git a/include/game_state.hpp b/include/game_state.hpp
index 67423b9..b289a6c 100644
--- a/include/game_state.hpp
+++ b/include/game_state.hpp
@@ -4,6 +4,16 @@
 #include "myassert.h"
 #include "game_state.h"
 
+/**
+ * Compiling with -DINTEGRITY_CHECK_ON will enable exhaustive integrity check while backtracking.
+ * These significantly slow down performance, so they are deactivated by default.
+ */
+#ifdef INTEGRITY_CHECK_ON
+#define CHECK_DRAW_PILE_INTEGRITY check_draw_pile_integrity()
+#else
+#define CHECK_DRAW_PILE_INTEGRITY
+#endif
+
 namespace Hanabi
 {
 
@@ -186,7 +196,7 @@ namespace Hanabi
   unsigned long
   HanabiState<num_suits, num_players, hand_size>::play_and_potentially_update(hand_index_t index, bool cycle)
   {
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     ASSERT(index < _hands[_turn].size());
     const Card played_card = _hands[_turn][index];
 
@@ -210,7 +220,7 @@ namespace Hanabi
     const unsigned long multiplicity = draw(index, cycle, !strike);
 
     incr_turn();
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     return multiplicity;
   }
 
@@ -224,7 +234,7 @@ namespace Hanabi
   unsigned long
   HanabiState<num_suits, num_players, hand_size>::discard_and_potentially_update(hand_index_t index, bool cycle)
   {
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     ASSERT(index < _hands[_turn].size());
     ASSERT(_num_clues != max_num_clues);
 
@@ -238,7 +248,7 @@ namespace Hanabi
     _actions_log.emplace(ActionType::discard, discarded_card, index);
 
     incr_turn();
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     return multiplicity;
   }
 
@@ -589,7 +599,7 @@ namespace Hanabi
   void
   HanabiState<num_suits, num_players, hand_size>::revert_play(bool cycle)
   {
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     const BacktrackAction last_action = _actions_log.top();
     _actions_log.pop();
     ASSERT(last_action.action_type == ActionType::play);
@@ -609,13 +619,13 @@ namespace Hanabi
       // If we misplayed, then we lost the card and have to regain it now
       _num_copies_left[last_action.discarded]++;
     }
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
   }
 
   template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
   void HanabiState<num_suits, num_players, hand_size>::revert_discard(bool cycle)
   {
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
     const BacktrackAction last_action = _actions_log.top();
     _actions_log.pop();
 
@@ -631,7 +641,7 @@ namespace Hanabi
     _num_copies_left[last_action.discarded]++;
 
     revert_draw(last_action.index, last_action.discarded, cycle, false);
-    check_draw_pile_integrity();
+    CHECK_DRAW_PILE_INTEGRITY;
   }
 
   template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
@@ -1190,7 +1200,7 @@ namespace Hanabi
     // encode number of clues
     clue_t const scaled_clues = clue_t(2) * _num_clues;
     assert(scaled_clues.denominator() == 1);
-    ret.push_back((clue_t(2) * _num_clues).numerator());
+    ret.push_back(scaled_clues.numerator());
 
     // we can encode draw pile size and extra turn in one metric, since we only have extra turns if draw pile is empty
     const std::uint8_t draw_pile_size_and_extra_turns = [this]() -> uint8_t {