diff --git a/src/arachne.c b/src/arachne.c
index 36ebf6b..824080d 100644
--- a/src/arachne.c
+++ b/src/arachne.c
@@ -187,7 +187,6 @@ create_intruder_goal (Term t)
   run = sys->maxruns - 1;
   rd = sys->runs[run].start;
   sys->runs[run].length = 1;
-  termDelete (rd->message);
   rd->message = termDuplicate (t);
 #ifdef DEBUG
   explanation = "Adding intruder goal for message ";
@@ -261,10 +260,14 @@ bind_new_run (const Goal goal, const Protocol p, const Role r,
   int run;
   int flag;
   Roledef rd;
+  int old_run;
+  int old_index;
 
   roleInstance (sys, p, r, NULL);
   run = sys->maxruns - 1;
   sys->runs[run].length = index + 1;
+  old_run = goal.rd->bind_run;
+  old_index = goal.rd->bind_index;
   goal.rd->bind_run = run;
   goal.rd->bind_index = index;
 #ifdef DEBUG
@@ -277,7 +280,8 @@ bind_new_run (const Goal goal, const Protocol p, const Role r,
 
   iterate ();
 
-  goal.rd->bind_run = INVALID;
+  goal.rd->bind_run = old_run;
+  goal.rd->bind_index = old_index;
   roleInstanceDestroy (sys);
   return flag;
 }
@@ -499,6 +503,15 @@ bind_goal (const Goal goal)
 int
 prune ()
 {
+  if (indentDepth > 2)
+    {
+      // Hardcoded limit on iterations
+#ifdef DEBUG
+      indentPrint ();
+      eprintf ("Pruned because too many iteration levels.\n");
+#endif
+      return 1;
+    }
   if (sys->maxruns > 5)
     {
       // Hardcoded limit on runs
diff --git a/src/mgu.c b/src/mgu.c
index a6e3900..8afcc63 100644
--- a/src/mgu.c
+++ b/src/mgu.c
@@ -173,20 +173,23 @@ termMguInTerm (Term t1, Term t2, int (*iterator) ())
 
   flag = 1;
   t2 = deVar (t2);
-  if (t2 != NULL && isTermTuple (t2))
+  if (t2 != NULL)
     {
-      // t2 is a tuple, consider interm options as well.
-      flag = flag && termMguInTerm (t1, t2->left.op1, iterator);
-      flag = flag && termMguInTerm (t1, t2->right.op2, iterator);
-    }
-  // simple clause or combined
-  tl = termMguTerm (t1, t2);
-  if (tl != MGUFAIL)
-    {
-      // Iterate
-      flag = flag && iterator (tl);
-      // Reset variables
-      termlistSubstReset (tl);
+      if (isTermTuple (t2))
+	{
+	  // t2 is a tuple, consider interm options as well.
+	  flag = flag && termMguInTerm (t1, t2->left.op1, iterator);
+	  flag = flag && termMguInTerm (t1, t2->right.op2, iterator);
+	}
+      // simple clause or combined
+      tl = termMguTerm (t1, t2);
+      if (tl != MGUFAIL)
+	{
+	  // Iterate
+	  flag = flag && iterator (tl);
+	  // Reset variables
+	  termlistSubstReset (tl);
+	}
     }
   return flag;
 }
diff --git a/src/system.c b/src/system.c
index e5299ca..445fbe8 100644
--- a/src/system.c
+++ b/src/system.c
@@ -269,9 +269,19 @@ ensureValidRun (const System sys, int run)
       myrun.step = 0;
       myrun.index = NULL;
       myrun.start = NULL;
-      myrun.know = knowledgeDuplicate (sys->know);
-      myrun.prevSymmRun = -1;
-      myrun.firstNonAgentRead = -1;
+      if (sys->engine == POR_ENGINE)
+	{
+	  myrun.know = knowledgeDuplicate (sys->know);
+	  myrun.prevSymmRun = -1;
+	  myrun.firstNonAgentRead = -1;
+	}
+      else
+	{
+	  // Arachne etc.
+	  myrun.know = NULL;
+	  myrun.prevSymmRun = -1;
+	  myrun.firstNonAgentRead = -1;
+	}
     }
 }