diff --git a/vvp/array.cc b/vvp/array.cc
index 3bc4688b1..a5c07bdcd 100644
--- a/vvp/array.cc
+++ b/vvp/array.cc
@@ -1028,8 +1028,11 @@ static vpiHandle vpip_make_array(char*label, const char*name,
       return &(obj->base);
 }
 
-void array_alias_word(vvp_array_t array, unsigned long addr, vpiHandle word)
+void array_alias_word(vvp_array_t array, unsigned long addr, vpiHandle word,
+                      int msb, int lsb)
 {
+      assert(array->msb.value == msb);
+      assert(array->lsb.value == lsb);
       assert(addr < array->array_count);
       assert(array->nets);
       array->nets[addr] = word;
diff --git a/vvp/array.h b/vvp/array.h
index 486213760..f834a6980 100644
--- a/vvp/array.h
+++ b/vvp/array.h
@@ -1,7 +1,7 @@
 #ifndef __array_H
 #define __array_H
 /*
- * Copyright (c) 2007-2008 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2007-2010 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -36,7 +36,7 @@ extern void array_word_change(vvp_array_t array, unsigned long addr);
 
 extern void array_attach_word(vvp_array_t array, unsigned addr, vpiHandle word);
 extern void array_alias_word(vvp_array_t array, unsigned long addr,
-                             vpiHandle word);
+                             vpiHandle word, int msb, int lsb);
 
 extern void array_set_word(vvp_array_t arr, unsigned idx,
 			    unsigned off, vvp_vector4_t val);
diff --git a/vvp/logic.cc b/vvp/logic.cc
index a47ffcbeb..e16dacfdf 100644
--- a/vvp/logic.cc
+++ b/vvp/logic.cc
@@ -675,7 +675,7 @@ void compile_functor(char*label, char*type, unsigned width,
       }
 
       vvp_net_t*net_drv = new vvp_net_t;
-      vvp_net_fun_t*obj_drv = new vvp_fun_drive(BIT4_X, ostr0, ostr1);
+      vvp_net_fun_t*obj_drv = new vvp_fun_drive(ostr0, ostr1);
       net_drv->fun = obj_drv;
 
 	/* Point the gate to the drive node. */
diff --git a/vvp/vvp_net.cc b/vvp/vvp_net.cc
index b1eef243b..5c574c514 100644
--- a/vvp/vvp_net.cc
+++ b/vvp/vvp_net.cc
@@ -2864,7 +2864,7 @@ void vvp_net_fun_t::force_flag(void)
 
 /* **** vvp_fun_drive methods **** */
 
-vvp_fun_drive::vvp_fun_drive(vvp_bit4_t /*init*/, unsigned str0, unsigned str1)
+vvp_fun_drive::vvp_fun_drive(unsigned str0, unsigned str1)
 {
       assert(str0 < 8);
       assert(str1 < 8);
diff --git a/vvp/vvp_net.h b/vvp/vvp_net.h
index 8a80e6e39..b421d566b 100644
--- a/vvp/vvp_net.h
+++ b/vvp/vvp_net.h
@@ -1328,7 +1328,7 @@ class vvp_fun_repeat  : public vvp_net_fun_t {
 class vvp_fun_drive  : public vvp_net_fun_t {
 
     public:
-      vvp_fun_drive(vvp_bit4_t init, unsigned str0 =6, unsigned str1 =6);
+      vvp_fun_drive(unsigned str0 =6, unsigned str1 =6);
       ~vvp_fun_drive();
 
       void recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit,
diff --git a/vvp/vvp_net_sig.cc b/vvp/vvp_net_sig.cc
index 7e5b7e87d..2e1a43270 100644
--- a/vvp/vvp_net_sig.cc
+++ b/vvp/vvp_net_sig.cc
@@ -308,8 +308,12 @@ const vvp_vector4_t& vvp_fun_signal4_sa::vec4_unfiltered_value() const
       return bits4_;
 }
 
-vvp_fun_signal4_aa::vvp_fun_signal4_aa(unsigned wid, vvp_bit4_t /*init */)
+vvp_fun_signal4_aa::vvp_fun_signal4_aa(unsigned wid, vvp_bit4_t init)
 {
+	/* To make init work we would need to save it and then use the
+	 * saved value when we ran reset_instance(). For now just make
+	 * sure it matches the value we use in reset_instance(). */
+      assert(init == BIT4_X);
       context_idx_ = vpip_add_item_to_context(this, vpip_peek_context_scope());
       size_ = wid;
 }
@@ -644,9 +648,12 @@ vvp_net_fil_t::prop_t vvp_wire_vec4::filter_vec4(const vvp_vector4_t&bit, vvp_ve
 
 vvp_net_fil_t::prop_t vvp_wire_vec4::filter_vec8(const vvp_vector8_t&bit,
                                                  vvp_vector8_t&rep,
-                                                 unsigned /*base */,
-                                                 unsigned /*vwid */)
+                                                 unsigned base,
+                                                 unsigned vwid)
 {
+	// For now there is no support for a non-zero base.
+      assert(0 == base);
+      assert(bits4_.size() == vwid);
       assert(bits4_.size() == bit.size());
       bits4_ = reduce4(bit);
       return filter_mask_(bit, vvp_vector8_t(force4_,6,6), rep, 0);
@@ -769,9 +776,13 @@ vvp_wire_vec8::vvp_wire_vec8(unsigned wid)
 
 vvp_net_fil_t::prop_t vvp_wire_vec8::filter_vec4(const vvp_vector4_t&bit,
                                                  vvp_vector4_t&rep,
-                                                 unsigned /*base */,
+                                                 unsigned base,
                                                  unsigned vwid)
 {
+	// For now there is no support for a non-zero base.
+      assert(0 == base);
+      assert(bits8_.size() == vwid);
+      assert(bits8_.size() == bit.size());
 	// QUESTION: Is it really correct to propagate a vec4 if this
 	// is a vec8 node? In fact, it is really possible for a vec4
 	// value to get through to a vec8 filter?
diff --git a/vvp/words.cc b/vvp/words.cc
index a82c3c772..de576e54c 100644
--- a/vvp/words.cc
+++ b/vvp/words.cc
@@ -493,7 +493,7 @@ void compile_aliasw(char*label, char*array_label, unsigned long array_addr,
 
       vpiHandle obj = vvp_lookup_handle(argv[0].text);
       assert(obj);
-      array_alias_word(array, array_addr, obj);
+      array_alias_word(array, array_addr, obj, msb, lsb);
 
       free(label);
       free(array_label);