diff --git a/src/arachne.c b/src/arachne.c
index 2b8a00e..c504077 100644
--- a/src/arachne.c
+++ b/src/arachne.c
@@ -57,8 +57,6 @@ Role I_RRSD;			//!< Decrypt role of the intruder
 
 int proofDepth;			//!< Current depth of the proof
 int max_encryption_level;	//!< Maximum encryption level of any term
-int num_regular_runs;		//!< Current number of regular runs
-int num_intruder_runs;		//!< Current number of intruder runs
 
 static int indentDepth;
 static int prevIndentDepth;
@@ -132,8 +130,8 @@ arachneInit (const System mysys)
   add_event (SEND, NULL);
   I_RRSD = add_role ("I_D: Decrypt");
 
-  num_regular_runs = 0;
-  num_intruder_runs = 0;
+  sys->num_regular_runs = 0;
+  sys->num_intruder_runs = 0;
   max_encryption_level = 0;
 
   indentDepth = 0;
@@ -309,9 +307,9 @@ semiRunCreate (const Protocol p, const Role r)
   int run;
 
   if (p == INTRUDER)
-    num_intruder_runs++;
+    sys->num_intruder_runs++;
   else
-    num_regular_runs++;
+    sys->num_regular_runs++;
 #ifdef DEBUG
   if (DEBUGL (5))
     {
@@ -341,9 +339,9 @@ semiRunDestroy ()
       p = sys->runs[sys->maxruns - 1].protocol;
       roleInstanceDestroy (sys);
       if (p == INTRUDER)
-	num_intruder_runs--;
+	sys->num_intruder_runs--;
       else
-	num_regular_runs--;
+	sys->num_regular_runs--;
     }
 }
 
@@ -2277,8 +2275,8 @@ arachne ()
       error ("Something is wrong, number of runs >0.");
     }
 
-  num_regular_runs = 0;
-  num_intruder_runs = 0;
+  sys->num_regular_runs = 0;
+  sys->num_intruder_runs = 0;
 
   max_encryption_level = 0;
   iterate_role_events (determine_encrypt_max);
diff --git a/src/binding.c b/src/binding.c
index 8302104..50f7226 100644
--- a/src/binding.c
+++ b/src/binding.c
@@ -588,3 +588,23 @@ bindings_c_minimal ()
   }
   return true;
 }
+
+//! Count the number of bindings that are done.
+int
+countBindingsDone ()
+{
+  int count;
+
+  int countDone (Binding b)
+  {
+    if (b->done)
+      {
+	count++;
+      }
+    return true;
+  }
+
+  count = 0;
+  iterate_bindings (countDone);
+  return count;
+}
diff --git a/src/binding.h b/src/binding.h
index 0ff5d51..34bb8b8 100644
--- a/src/binding.h
+++ b/src/binding.h
@@ -48,5 +48,6 @@ int iterate_preceding_bindings (const int run, const int ev,
 				int (*func) (Binding b));
 
 int bindings_c_minimal ();
+int countBindingsDone ();
 
 #endif
diff --git a/src/cost.c b/src/cost.c
index 38e6adf..48459ff 100644
--- a/src/cost.c
+++ b/src/cost.c
@@ -32,10 +32,14 @@ attackCost (const System sys)
 
   cost = 0;
 
-  cost += get_semitrace_length ();
-  cost += 8 * selfInitiators (sys);
-  cost += 4 * selfResponders (sys);
-  cost += 2 * countInitiators (sys);
+  //cost += get_semitrace_length ();
+
+  cost += 10 * selfInitiators (sys);
+  cost += 7 * selfResponders (sys);
+  cost += 4 * sys->num_regular_runs;
+  cost += 3 * countInitiators (sys);
+  cost += 2 * countBindingsDone ();
+  cost += 1 * sys->num_intruder_runs;
 
   return cost;
 }
diff --git a/src/prune_bounds.c b/src/prune_bounds.c
index 4e56d59..4db30f5 100644
--- a/src/prune_bounds.c
+++ b/src/prune_bounds.c
@@ -17,8 +17,6 @@ extern int attack_leastcost;
 extern Protocol INTRUDER;
 extern int proofDepth;
 extern int max_encryption_level;
-extern int num_regular_runs;
-extern int num_intruder_runs;
 
 //! Prune determination for bounds
 /**
@@ -92,13 +90,14 @@ prune_bounds (const System sys)
 	}
     }
 
-  if (num_regular_runs > switches.runs)
+  if (sys->num_regular_runs > switches.runs)
     {
       // Hardcoded limit on runs
       if (switches.output == PROOF)
 	{
 	  indentPrint ();
-	  eprintf ("Pruned: too many regular runs (%i).\n", num_regular_runs);
+	  eprintf ("Pruned: too many regular runs (%i).\n",
+		   sys->num_regular_runs);
 	}
       return 1;
     }
@@ -111,7 +110,7 @@ prune_bounds (const System sys)
   if (switches.experimental & 1)
     {
       if ((switches.match < 2)
-	  && (num_intruder_runs >
+	  && (sys->num_intruder_runs >
 	      ((double) switches.runs * max_encryption_level * 8)))
 	{
 	  // Hardcoded limit on iterations
@@ -120,7 +119,7 @@ prune_bounds (const System sys)
 	      indentPrint ();
 	      eprintf
 		("Pruned: %i intruder runs is too much. (max encr. level %i)\n",
-		 num_intruder_runs, max_encryption_level);
+		 sys->num_intruder_runs, max_encryption_level);
 	    }
 	  return 1;
 	}
diff --git a/src/system.c b/src/system.c
index 99fc117..b8c8897 100644
--- a/src/system.c
+++ b/src/system.c
@@ -107,6 +107,8 @@ systemReset (const System sys)
 
   termlistDestroy (sys->secrets);	// remove old secrets list
   sys->secrets = NULL;		// list of claimed secrets
+  sys->num_intruder_runs = 0;	// number of intruder runs
+  sys->num_regular_runs = 0;	// number of regular runs
 
   /* transfer switches */
   sys->maxtracelength = switches.maxtracelength;
diff --git a/src/system.h b/src/system.h
index 1288711..0a0e1c6 100644
--- a/src/system.h
+++ b/src/system.h
@@ -121,6 +121,8 @@ struct system
   states_t failed;		//!< Number of claims failed.
   int attackid;			//!< Global counter of attacks (used for assigning identifiers) within this Scyther call.
   int countScenario;		//!< Number of scenarios skipped.
+  int num_regular_runs;		//!< Number of regular runs
+  int num_intruder_runs;	//!< Number of intruder runs
 
   /* protocol definition */
   Protocol protocols;		//!< List of protocols in the system