diff --git a/wrap/Module.cpp b/wrap/Module.cpp
index 4fc53268c..6154a2178 100644
--- a/wrap/Module.cpp
+++ b/wrap/Module.cpp
@@ -217,21 +217,27 @@ void Module::parseMarkup(const std::string& data) {
  
   Rule namespace_ret_p = namespace_name_p[push_back_a(namespaces_return)] >> str_p("::"); 
  
-//  Rule returnType1_p =
-//    (basisType_p[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::BASIS)]) |
-//    ((*namespace_ret_p)[assign_a(retVal.namespaces1, namespaces_return)][clear_a(namespaces_return)]
-//        >> (className_p[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::CLASS)]) >>
-//        !ch_p('*')[assign_a(retVal.isPtr1,true)]) |
-//    (eigenType_p[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::EIGEN)])
-//    | str_p("void")[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::VOID)]; // FIXME: allows for void in a pair
+  // const values
+  static const ReturnValue::return_category RETURN_EIGEN = ReturnValue::EIGEN;
+  static const ReturnValue::return_category RETURN_BASIS = ReturnValue::BASIS;
+  static const ReturnValue::return_category RETURN_CLASS = ReturnValue::CLASS;
+  static const ReturnValue::return_category RETURN_VOID = ReturnValue::VOID;
 
-  // current revision
+  // alternate version 1
+//  Rule returnType1_p =
+//    basisType_p[assign_a(retVal.category1, ReturnValue::BASIS)][assign_a(retVal.type1)] |
+//    eigenType_p[assign_a(retVal.category1, ReturnValue::EIGEN)][assign_a(retVal.type1)] |
+//    ((*namespace_ret_p)[assign_a(retVal.namespaces1, namespaces_return)][clear_a(namespaces_return)]
+//            >> (className_p[assign_a(retVal.category1, ReturnValue::CLASS)][assign_a(retVal.type1)]) >>
+//            !ch_p('*')[assign_a(retVal.isPtr1,true)]);
+
+  // switching to using constants
   Rule returnType1_p =
-    basisType_p[assign_a(retVal.category1, ReturnValue::BASIS)][assign_a(retVal.type1)] |
+    (basisType_p[assign_a(retVal.type1)][assign_a(retVal.category1, RETURN_BASIS)]) |
     ((*namespace_ret_p)[assign_a(retVal.namespaces1, namespaces_return)][clear_a(namespaces_return)]
-            >> (className_p[assign_a(retVal.category1, ReturnValue::CLASS)][assign_a(retVal.type1)]) >>
-            !ch_p('*')[assign_a(retVal.isPtr1,true)]) |
-    eigenType_p[assign_a(retVal.category1, ReturnValue::EIGEN)][assign_a(retVal.type1)];
+        >> (className_p[assign_a(retVal.type1)][assign_a(retVal.category1, RETURN_CLASS)]) >>
+        !ch_p('*')[assign_a(retVal.isPtr1,true)]) |
+    (eigenType_p[assign_a(retVal.type1)][assign_a(retVal.category1, RETURN_EIGEN)]);
 
   // Original
 //  Rule returnType1_p =
@@ -240,22 +246,29 @@ void Module::parseMarkup(const std::string& data) {
 //        >> (className_p[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::CLASS)]) >>
 //        !ch_p('*')[assign_a(retVal.isPtr1,true)]) |
 //    (eigenType_p[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::EIGEN)]);
- 
+
   Rule returnType2_p = 
-    (basisType_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::BASIS)]) | 
+    (basisType_p[assign_a(retVal.type2)][assign_a(retVal.category2, RETURN_BASIS)]) |
     ((*namespace_ret_p)[assign_a(retVal.namespaces2, namespaces_return)][clear_a(namespaces_return)] 
-        >> (className_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::CLASS)]) >> 
+        >> (className_p[assign_a(retVal.type2)][assign_a(retVal.category2, RETURN_CLASS)]) >>
         !ch_p('*')  [assign_a(retVal.isPtr2,true)]) | 
-    (eigenType_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::EIGEN)]); 
+    (eigenType_p[assign_a(retVal.type2)][assign_a(retVal.category2, RETURN_EIGEN)]);
+
+  // Original
+//  Rule returnType2_p =
+//    (basisType_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::BASIS)]) |
+//    ((*namespace_ret_p)[assign_a(retVal.namespaces2, namespaces_return)][clear_a(namespaces_return)]
+//        >> (className_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::CLASS)]) >>
+//        !ch_p('*')  [assign_a(retVal.isPtr2,true)]) |
+//    (eigenType_p[assign_a(retVal.type2)][assign_a(retVal.category2, ReturnValue::EIGEN)]);
  
   Rule pair_p =  
     (str_p("pair") >> '<' >> returnType1_p >> ',' >> returnType2_p >> '>') 
     [assign_a(retVal.isPair,true)]; 
  
-  Rule void_p = str_p("void")[assign_a(retVal.type1)][assign_a(retVal.category1, ReturnValue::VOID)];
+  Rule void_p = str_p("void")[assign_a(retVal.type1)][assign_a(retVal.category1, RETURN_VOID)];
  
-  Rule returnType_p = void_p | returnType1_p | pair_p; // original
-//  Rule returnType_p = returnType1_p | pair_p;
+  Rule returnType_p = void_p | returnType1_p | pair_p;
  
   Rule methodName_p = lexeme_d[lower_p >> *(alnum_p | '_')]; 
  
diff --git a/wrap/ReturnValue.cpp b/wrap/ReturnValue.cpp
index c7902e60f..3cb68181b 100644
--- a/wrap/ReturnValue.cpp
+++ b/wrap/ReturnValue.cpp
@@ -55,12 +55,6 @@ void ReturnValue::wrap_result(const string& result, FileWriter& file, const Type
     // For a pair, store the returned pair so we do not evaluate the function twice
     file.oss << "  " << return_type(false, pair) << " pairResult = " << result << ";\n";
     
-    // sanity check values
-    if ((category1 != ReturnValue::CLASS) || (category1 != ReturnValue::EIGEN) || (category1 != ReturnValue::BASIS))
-      throw invalid_argument("ReturnValue::wrap_result() FAILURE: invalid first member of pair ");
-    if ((category2 != ReturnValue::CLASS) || (category2 != ReturnValue::EIGEN) || (category2 != ReturnValue::BASIS))
-       throw invalid_argument("ReturnValue::wrap_result() FAILURE: invalid second member of pair ");
-
     // first return value in pair
     if (category1 == ReturnValue::CLASS) { // if we are going to make one
       string objCopy, ptrType;
@@ -107,9 +101,6 @@ void ReturnValue::wrap_result(const string& result, FileWriter& file, const Type
     } else
       file.oss << "  out[1] = wrap< " << return_type(true,arg2) << " >(pairResult.second);\n";
   } else { // Not a pair
-    // sanity check values
-    if ((category1 != ReturnValue::CLASS) || (category1 != ReturnValue::EIGEN) || (category1 != ReturnValue::BASIS))
-      throw invalid_argument("ReturnValue::wrap_result() FAILURE: return non-void flag ");
 
     if (category1 == ReturnValue::CLASS) {
       string objCopy, ptrType;
diff --git a/wrap/ReturnValue.h b/wrap/ReturnValue.h
index f83ff507f..7a677532f 100644
--- a/wrap/ReturnValue.h
+++ b/wrap/ReturnValue.h
@@ -24,13 +24,12 @@ struct ReturnValue {
     CLASS = 1,
     EIGEN = 2,
     BASIS = 3,
-    VOID  = 4,
-    DUMMY_CATEGORY = 5
+    VOID  = 4
   } return_category;
 
   ReturnValue(bool enable_verbosity = true)
   : verbose(enable_verbosity), isPtr1(false), isPtr2(false),
-    isPair(false), category1(DUMMY_CATEGORY), category2(DUMMY_CATEGORY)
+    isPair(false), category1(CLASS), category2(CLASS)
   {}
 
   bool verbose;