diff --git a/elab_expr.cc b/elab_expr.cc
index e8cf64fdc..2be59cac1 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -3885,7 +3885,9 @@ NetExpr* PEIdent::elaborate_expr_net_part_(Design*des, NetScope*scope,
 	    unsigned long lwid, mwid;
 	    bool lrc;
 	    lrc = net->sig()->sb_to_slice(prefix_indices, lsv, loff, lwid);
+	    ivl_assert(*this, lrc);
 	    lrc = net->sig()->sb_to_slice(prefix_indices, msv, moff, mwid);
+	    ivl_assert(*this, lrc);
 
 	    if (moff > loff) {
 		  sb_lsb = loff;
diff --git a/elab_lval.cc b/elab_lval.cc
index f53acc58d..c0d470d51 100644
--- a/elab_lval.cc
+++ b/elab_lval.cc
@@ -311,7 +311,7 @@ NetAssign_* PEIdent::elaborate_lval(Design*des,
       return lv;
 }
 
-NetAssign_* PEIdent::elaborate_lval_method_class_member_(Design*des,
+NetAssign_* PEIdent::elaborate_lval_method_class_member_(Design*,
 							 NetScope*scope) const
 {
       if (!gn_system_verilog())
@@ -617,7 +617,9 @@ bool PEIdent::elaborate_lval_net_part_(Design*des,
 	    bool lrc;
 	    unsigned long tmp_lwid, tmp_mwid;
 	    lrc = reg->sb_to_slice(prefix_indices,lsb, loff, tmp_lwid);
+	    ivl_assert(*this, lrc);
 	    lrc = reg->sb_to_slice(prefix_indices,msb, moff, tmp_mwid);
+	    ivl_assert(*this, lrc);
 
 	    if (loff < moff) {
 		  moff = moff + tmp_mwid - 1;
diff --git a/elab_type.cc b/elab_type.cc
index 779bb1e9a..7ddb9453f 100644
--- a/elab_type.cc
+++ b/elab_type.cc
@@ -72,7 +72,7 @@ ivl_type_s* atom2_type_t::elaborate_type(Design*des, NetScope*) const
       }
 }
 
-ivl_type_s* class_type_t::elaborate_type(Design*des, NetScope*scope) const
+ivl_type_s* class_type_t::elaborate_type(Design*, NetScope*scope) const
 {
       return scope->find_class(name);
 }
diff --git a/pform_string_type.cc b/pform_string_type.cc
index 593950af5..569056764 100644
--- a/pform_string_type.cc
+++ b/pform_string_type.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2012-2013 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
@@ -21,7 +21,7 @@
 # include  "parse_misc.h"
 # include  "ivl_assert.h"
 
-static void pform_set_string_type(string_type_t*string_type, perm_string name, NetNet::Type net_type, list<named_pexpr_t>*attr)
+static void pform_set_string_type(string_type_t*, perm_string name, NetNet::Type net_type, list<named_pexpr_t>*attr)
 {
       PWire*net = pform_get_make_wire_in_scope(name, net_type, NetNet::NOT_A_PORT, IVL_VT_STRING);
       pform_bind_attributes(net->attributes, attr, true);
diff --git a/vhdlpp/expression_evaluate.cc b/vhdlpp/expression_evaluate.cc
index 2671b23f0..56b631006 100644
--- a/vhdlpp/expression_evaluate.cc
+++ b/vhdlpp/expression_evaluate.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2011-2013 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
@@ -119,7 +119,7 @@ bool ExpAttribute::evaluate(Entity*, Architecture*arc, int64_t&val) const
  * I don't yet know how to evaluate concatenations. It is not likely
  * to come up anyhow.
  */
-bool ExpConcat::evaluate(ScopeBase*scope, int64_t&val) const
+bool ExpConcat::evaluate(ScopeBase*, int64_t&) const
 {
       return false;
 }
diff --git a/vvp/vpi_callback.cc b/vvp/vpi_callback.cc
index c2accdd06..a847b5785 100644
--- a/vvp/vpi_callback.cc
+++ b/vvp/vpi_callback.cc
@@ -828,7 +828,7 @@ void vvp_wire_real::get_signal_value(struct t_vpi_value*vp)
       real_signal_value(vp, real_value());
 }
 
-void vvp_fun_signal_string_aa::get_signal_value(struct t_vpi_value*vp)
+void vvp_fun_signal_string_aa::get_signal_value(struct t_vpi_value*)
 {
       assert(0);
 }
diff --git a/vvp/vthread.cc b/vvp/vthread.cc
index c587e89c6..e96f9930e 100644
--- a/vvp/vthread.cc
+++ b/vvp/vthread.cc
@@ -168,11 +168,11 @@ struct vthread_s {
     private:
       enum { STACK_OBJ_MAX_SIZE = 32 };
       vvp_object_t stack_obj_[STACK_OBJ_MAX_SIZE];
-      int stack_obj_size_;
+      unsigned stack_obj_size_;
     public:
       inline vvp_object_t& peek_object(void)
       {
-	    assert(stack_obj_size_  > 0);
+	    assert(stack_obj_size_ > 0);
 	    return stack_obj_[stack_obj_size_-1];
       }
       inline void pop_object(vvp_object_t&obj)