diff --git a/src/scytherprof b/src/scytherprof
new file mode 100755
index 0000000..4881b5e
--- /dev/null
+++ b/src/scytherprof
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+scons gprof=yes
+./scyther $*
+gprof --flat-profile scyther
diff --git a/src/termlists.c b/src/termlists.c
index 838fc6f..d5900f1 100644
--- a/src/termlists.c
+++ b/src/termlists.c
@@ -109,25 +109,28 @@ termlistDestroy (Termlist tl)
 
 //! Determine whether a term is an element of a termlist.
 /**
+ * Term must be non-null.
+ *
  *@return True iff the term is an element of the termlist.
  */
-int
-inTermlist (Termlist tl, Term term)
+__inline__ int
+inTermlist (Termlist tl, const Term term)
 {
-  if (tl == NULL)
+#ifdef DEBUG
+  if (term == NULL)
     {
-      if (term == NULL)
-	return 1;
-      else
-	return 0;
+      error ("Trying to do inTermlist for a NULL term.");
     }
-  else
+#endif
+  while (tl != NULL)
     {
       if (isTermEqual (tl->term, term))
-	return 1;
-      else
-	return inTermlist (tl->next, term);
+	{
+	  return 1;
+	}
+      tl = tl->next;
     }
+  return 0;
 }
 
 //! Equality of two term lists.
diff --git a/src/termlists.h b/src/termlists.h
index 1a2c7cf..908bb26 100644
--- a/src/termlists.h
+++ b/src/termlists.h
@@ -28,7 +28,7 @@ Termlist termlistShallow (Termlist tl);
 void termlistDelete (Termlist tl);
 void termlistDestroy (Termlist tl);
 void termlistPrint (Termlist tl);
-int inTermlist (Termlist tl, Term term);
+int inTermlist (Termlist tl, const Term term);
 int isTermlistEqual (Termlist tl1, Termlist tl2);
 Termlist termlistAdd (Termlist tl, Term term);
 Termlist termlistAppend (const Termlist tl, const Term term);