diff --git a/sv_vpi_user.h b/sv_vpi_user.h
index e6e20b527..606f7f73f 100644
--- a/sv_vpi_user.h
+++ b/sv_vpi_user.h
@@ -1,7 +1,7 @@
 #ifndef __sv_vpi_user_H
 #define __sv_vpi_user_H
 /*
- * Copyright (c) 2010 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2010-2011 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
@@ -54,6 +54,9 @@ EXTERN_C_START
 #define vpiEnumTypespec     633
 #define vpiEnumConst        634
 
+/********* One-to-One ***********/
+#define vpiBaseTypespec     703
+
 /********* Many-to-One ***********/
 #define vpiMember           742
 
diff --git a/vvp/enum_type.cc b/vvp/enum_type.cc
index 561d063b0..b59b74641 100644
--- a/vvp/enum_type.cc
+++ b/vvp/enum_type.cc
@@ -43,6 +43,7 @@ static struct enumconst_s* enumconst_from_handle(vpiHandle obj)
 struct __vpiEnumTypespec {
       struct __vpiHandle base;
       std::vector<enumconst_s> names;
+      int base_type_code;
       bool is_signed;
 };
 
@@ -63,6 +64,13 @@ static int enum_type_get(int code, vpiHandle obj)
 	  case vpiSize:
 	    return ref->names.size();
 
+	    /* This is not currently set correctly. We always use vpiReg for
+	     * four state variables and vpiBitVar for two state variables.
+	     * This minimal functionality is needed to get the next() and
+	     * prev() methods to work correctly with invalid values. */
+	  case vpiBaseTypespec:
+	    return ref->base_type_code;
+
 	  case vpiSigned:
 	    return ref->is_signed;
 
@@ -163,6 +171,7 @@ void compile_enum2_type(char*label, long width, bool signed_flag,
       spec->base.vpi_type = &enum_type_rt;
       spec->names = std::vector<enumconst_s> (names->size());
       spec->is_signed = signed_flag;
+      spec->base_type_code = vpiBitVar;
 
       size_t idx = 0;
       for (list<struct enum_name_s>::iterator cur = names->begin()
@@ -188,6 +197,7 @@ void compile_enum4_type(char*label, long width, bool signed_flag,
       spec->base.vpi_type = &enum_type_rt;
       spec->names = std::vector<enumconst_s> (names->size());
       spec->is_signed = signed_flag;
+      spec->base_type_code = vpiReg;
 
       size_t idx = 0;
       for (list<struct enum_name_s>::iterator cur = names->begin()