diff --git a/compiler/cpp/Makefile.am b/compiler/cpp/Makefile.am
index 5082033..482a89a 100644
--- a/compiler/cpp/Makefile.am
+++ b/compiler/cpp/Makefile.am
@@ -111,7 +111,7 @@
                   src/thrift/generate/t_rs_generator.cc
 
 thrift_CPPFLAGS = -I$(srcdir)/src
-thrift_CXXFLAGS = -Wall -Wextra -pedantic
+thrift_CXXFLAGS = -Wall -Wextra -pedantic -Werror
 thrift_LDADD = @LEXLIB@ src/thrift/libparse.a
 
 if !WITH_PLUGIN
diff --git a/compiler/cpp/src/thrift/generate/t_csharp_generator.cc b/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
index 10d28b2..a6cb09d 100644
--- a/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_csharp_generator.cc
@@ -2909,6 +2909,7 @@
                                                      const string& structname) {
   // begin new scope
   member_mapping_scope dummy;
+  dummy.scope_member = 0;
   member_mapping_scopes.push_back(dummy);
   member_mapping_scope& active = member_mapping_scopes.back();
   active.scope_member = scope;
diff --git a/compiler/cpp/src/thrift/generate/t_haxe_generator.cc b/compiler/cpp/src/thrift/generate/t_haxe_generator.cc
index 4de4307..97c7d19 100644
--- a/compiler/cpp/src/thrift/generate/t_haxe_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_haxe_generator.cc
@@ -2556,6 +2556,7 @@
         if (!(tkey->is_binary())) {
           return "StringMap< " + type_name(tval) + ">";
         }
+        break; // default to ObjectMap<>
       case t_base_type::TYPE_I8:
       case t_base_type::TYPE_I16:
       case t_base_type::TYPE_I32:
@@ -2581,6 +2582,7 @@
         if (!(tkey->is_binary())) {
           return "StringSet";
         }
+        break; // default to ObjectSet
       case t_base_type::TYPE_I8:
       case t_base_type::TYPE_I16:
       case t_base_type::TYPE_I32:
diff --git a/compiler/cpp/src/thrift/generate/t_hs_generator.cc b/compiler/cpp/src/thrift/generate/t_hs_generator.cc
index 29c0816..30eb8fa 100644
--- a/compiler/cpp/src/thrift/generate/t_hs_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_hs_generator.cc
@@ -1415,12 +1415,12 @@
 
   } else if (ttype->is_set()) {
     out << "(Set.fromList $ P.map (\\" << val << " -> ";
-    generate_deserialize_type(out, ((t_map*)ttype)->get_key_type(), val);
+    generate_deserialize_type(out, ((t_set*)ttype)->get_elem_type(), val);
     out << ") " << arg << ")";
 
   } else if (ttype->is_list()) {
     out << "(Vector.fromList $ P.map (\\" << val << " -> ";
-    generate_deserialize_type(out, ((t_map*)ttype)->get_key_type(), val);
+    generate_deserialize_type(out, ((t_list*)ttype)->get_elem_type(), val);
     out << ") " << arg << ")";
   }
 }
@@ -1488,9 +1488,9 @@
     out << ")) $ Map.toList " << prefix;
 
   } else if (ttype->is_set()) {
-    out << "T.TSet " << type_to_enum(((t_list*)ttype)->get_elem_type());
+    out << "T.TSet " << type_to_enum(((t_set*)ttype)->get_elem_type());
     out << " $ P.map (\\" << v << " -> ";
-    generate_serialize_type(out, ((t_list*)ttype)->get_elem_type(), v);
+    generate_serialize_type(out, ((t_set*)ttype)->get_elem_type(), v);
     out << ") $ Set.toList " << prefix;
 
   } else if (ttype->is_list()) {
@@ -1577,7 +1577,7 @@
     return "(T.T_MAP " + ktype + " " + vtype + ")";
 
   } else if (type->is_set()) {
-    return "(T.T_SET " + type_to_enum(((t_list*)type)->get_elem_type()) + ")";
+    return "(T.T_SET " + type_to_enum(((t_set*)type)->get_elem_type()) + ")";
 
   } else if (type->is_list()) {
     return "(T.T_LIST " + type_to_enum(((t_list*)type)->get_elem_type()) + ")";
diff --git a/compiler/cpp/src/thrift/generate/t_netcore_generator.cc b/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
index 71e4236..8d157a9 100644
--- a/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_netcore_generator.cc
@@ -2789,6 +2789,7 @@
 {
     // begin new scope
     member_mapping_scope dummy;
+    dummy.scope_member = 0;
     member_mapping_scopes.push_back(dummy);
     member_mapping_scope& active = member_mapping_scopes.back();
     active.scope_member = scope;
diff --git a/compiler/cpp/src/thrift/parse/t_typedef.h b/compiler/cpp/src/thrift/parse/t_typedef.h
index 0cccc26..aad3a50 100644
--- a/compiler/cpp/src/thrift/parse/t_typedef.h
+++ b/compiler/cpp/src/thrift/parse/t_typedef.h
@@ -33,7 +33,7 @@
 class t_typedef : public t_type {
 public:
   t_typedef(t_program* program, t_type* type, const std::string& symbolic)
-    : t_type(program, symbolic), type_(type), symbolic_(symbolic), forward_(false), seen_(false) {}
+    : t_type(program, symbolic), type_(type), symbolic_(symbolic), forward_(false) {}
 
   /**
    * This constructor is used to refer to a type that is lazily
@@ -44,8 +44,8 @@
     : t_type(program, symbolic),
       type_(NULL),
       symbolic_(symbolic),
-      forward_(forward),
-      seen_(false) {}
+      forward_(forward)
+  {}
 
   ~t_typedef() {}
 
@@ -61,7 +61,6 @@
   t_type* type_;
   std::string symbolic_;
   bool forward_;
-  mutable bool seen_;
 };
 
 #endif