diff --git a/src/system.c b/src/system.c
index 4c3623e..985f737 100644
--- a/src/system.c
+++ b/src/system.c
@@ -656,6 +656,9 @@ roleInstance (const System sys, const Protocol protocol, const Role role,
   runs[rid].locals = tolist;
   runs[rid].artefacts = artefacts;
 
+  /* erase any substitutions in the role definition, as they are now copied */
+  termlistSubstReset (role->variables);
+
   /* Determine symmetric run */
   runs[rid].prevSymmRun = staticRunSymmetry (sys, rid);	// symmetry reduction static analysis
 
diff --git a/src/termlist.c b/src/termlist.c
index f7a5b76..bbbb360 100644
--- a/src/termlist.c
+++ b/src/termlist.c
@@ -774,3 +774,19 @@ termlistOrder (Termlist tl1, Termlist tl2)
   else
     return 1;
 }
+
+//! Iterate over terms in termlist
+/**
+ * Function gets terms
+ */
+int
+termlist_iterate (Termlist tl, int (*func) ())
+{
+  while (tl != NULL)
+    {
+      if (!func (tl->term))
+	return 0;
+      tl = tl->next;
+    }
+  return 1;
+}
diff --git a/src/termlist.h b/src/termlist.h
index 73e2f03..a20e5c5 100644
--- a/src/termlist.h
+++ b/src/termlist.h
@@ -54,5 +54,6 @@ int validSubst (const int matchmode, const Term term);
 Term termFunction (Termlist fromlist, Termlist tolist, Term tx);
 Termlist termlistForward (Termlist tl);
 int termlistOrder (Termlist tl1, Termlist tl2);
+int termlist_iterate (Termlist tl, int (*func) ());
 
 #endif