diff -ru protobuf-3.0.0/src/google/protobuf/compiler/cpp/cpp_message.cc protobuf1/src/google/protobuf/compiler/cpp/cpp_message.cc
--- protobuf-3.0.0/src/google/protobuf/compiler/cpp/cpp_message.cc	2016-09-05 14:20:49.000000000 +0100
+++ protobuf1/src/google/protobuf/compiler/cpp/cpp_message.cc	2016-09-05 14:30:47.284339055 +0100
@@ -1762,17 +1762,20 @@
 void MessageGenerator::
 GenerateShutdownCode(io::Printer* printer) {
   printer->Print(
-    "delete $classname$::default_instance_;\n",
+    "delete $classname$::default_instance_;\n"
+    "$classname$::default_instance_ = NULL\n",
     "classname", classname_);
 
   if (HasDescriptorMethods(descriptor_->file(), options_)) {
     if (descriptor_->oneof_decl_count() > 0) {
       printer->Print(
-        "delete $classname$_default_oneof_instance_;\n",
+        "delete $classname$_default_oneof_instance_;\n"
+        "$classname$_default_oneof_instance_ = NULL;\n",
         "classname", classname_);
     }
     printer->Print(
-      "delete $classname$_reflection_;\n",
+      "delete $classname$_reflection_;\n"
+      "$classname$_reflection_ = NULL;\n",
       "classname", classname_);
   }
 
diff -ru protobuf-3.0.0/src/google/protobuf/compiler/cpp/cpp_string_field.cc protobuf1/src/google/protobuf/compiler/cpp/cpp_string_field.cc
--- protobuf-3.0.0/src/google/protobuf/compiler/cpp/cpp_string_field.cc	2016-07-27 22:40:30.000000000 +0100
+++ protobuf1/src/google/protobuf/compiler/cpp/cpp_string_field.cc	2016-09-05 14:25:17.645138524 +0100
@@ -360,7 +360,8 @@
 GenerateShutdownCode(io::Printer* printer) const {
   if (!descriptor_->default_value_string().empty()) {
     printer->Print(variables_,
-      "delete $classname$::$default_variable$;\n");
+      "delete $classname$::$default_variable$;\n"
+      "$classname$::$default_variable$ = NULL;\n");
   }
 }
 
diff -ru protobuf-3.0.0/src/google/protobuf/compiler/plugin.pb.cc protobuf1/src/google/protobuf/compiler/plugin.pb.cc
--- protobuf-3.0.0/src/google/protobuf/compiler/plugin.pb.cc	2016-07-27 22:40:30.000000000 +0100
+++ protobuf1/src/google/protobuf/compiler/plugin.pb.cc	2016-09-05 14:25:17.645138524 +0100
@@ -118,11 +118,17 @@
 
 void protobuf_ShutdownFile_google_2fprotobuf_2fcompiler_2fplugin_2eproto() {
   delete CodeGeneratorRequest::default_instance_;
+  CodeGeneratorRequest::default_instance_ = NULL;
   delete CodeGeneratorRequest_reflection_;
+  CodeGeneratorRequest_reflection_ = NULL;
   delete CodeGeneratorResponse::default_instance_;
+  CodeGeneratorResponse::default_instance_ = NULL;
   delete CodeGeneratorResponse_reflection_;
+  CodeGeneratorResponse_reflection_ = NULL;
   delete CodeGeneratorResponse_File::default_instance_;
+  CodeGeneratorResponse_File::default_instance_ = NULL;
   delete CodeGeneratorResponse_File_reflection_;
+  CodeGeneratorResponse_File_reflection_ = NULL;
 }
 
 void protobuf_AddDesc_google_2fprotobuf_2fcompiler_2fplugin_2eproto() GOOGLE_ATTRIBUTE_COLD;
diff -ru protobuf-3.0.0/src/google/protobuf/descriptor.pb.cc protobuf1/src/google/protobuf/descriptor.pb.cc
--- protobuf-3.0.0/src/google/protobuf/descriptor.pb.cc	2016-07-27 22:40:30.000000000 +0100
+++ protobuf1/src/google/protobuf/descriptor.pb.cc	2016-09-05 14:44:42.770764933 +0100
@@ -648,57 +648,106 @@
 
 void protobuf_ShutdownFile_google_2fprotobuf_2fdescriptor_2eproto() {
   delete FileDescriptorSet::default_instance_;
+  FileDescriptorSet::default_instance_ = NULL;
   delete FileDescriptorSet_reflection_;
+  FileDescriptorSet_reflection_ = NULL;
   delete FileDescriptorProto::default_instance_;
+  FileDescriptorProto::default_instance_ = NULL;
   delete FileDescriptorProto_reflection_;
+  FileDescriptorProto_reflection_ = NULL;
   delete DescriptorProto::default_instance_;
+  DescriptorProto::default_instance_ = NULL;
   delete DescriptorProto_reflection_;
+  DescriptorProto_reflection_ = NULL;
   delete DescriptorProto_ExtensionRange::default_instance_;
+  DescriptorProto_ExtensionRange::default_instance_ = NULL;
   delete DescriptorProto_ExtensionRange_reflection_;
+  DescriptorProto_ExtensionRange_reflection_ = NULL;
   delete DescriptorProto_ReservedRange::default_instance_;
+  DescriptorProto_ReservedRange::default_instance_ = NULL;
   delete DescriptorProto_ReservedRange_reflection_;
+  DescriptorProto_ReservedRange_reflection_ = NULL;
   delete FieldDescriptorProto::default_instance_;
+  FieldDescriptorProto::default_instance_ = NULL;
   delete FieldDescriptorProto_reflection_;
+  FieldDescriptorProto_reflection_ = NULL;
   delete OneofDescriptorProto::default_instance_;
+  OneofDescriptorProto::default_instance_ = NULL;
   delete OneofDescriptorProto_reflection_;
+  OneofDescriptorProto_reflection_ = NULL;
   delete EnumDescriptorProto::default_instance_;
+  EnumDescriptorProto::default_instance_ = NULL;
   delete EnumDescriptorProto_reflection_;
+  EnumDescriptorProto_reflection_ = NULL;
   delete EnumValueDescriptorProto::default_instance_;
+  EnumValueDescriptorProto::default_instance_ = NULL;
   delete EnumValueDescriptorProto_reflection_;
+  EnumValueDescriptorProto_reflection_ = NULL;
   delete ServiceDescriptorProto::default_instance_;
+  ServiceDescriptorProto::default_instance_ = NULL;
   delete ServiceDescriptorProto_reflection_;
+  ServiceDescriptorProto_reflection_ = NULL;
   delete MethodDescriptorProto::default_instance_;
+  MethodDescriptorProto::default_instance_ = NULL;
   delete MethodDescriptorProto_reflection_;
+  MethodDescriptorProto_reflection_ = NULL;
   delete FileOptions::default_instance_;
+  FileOptions::default_instance_ = NULL;
   delete FileOptions_reflection_;
+  FileOptions_reflection_ = NULL;
   delete MessageOptions::default_instance_;
+  MessageOptions::default_instance_ = NULL;
   delete MessageOptions_reflection_;
+  MessageOptions_reflection_ = NULL;
   delete FieldOptions::default_instance_;
+  FieldOptions::default_instance_ = NULL;
   delete FieldOptions_reflection_;
+  FieldOptions_reflection_ = NULL;
   delete OneofOptions::default_instance_;
+  OneofOptions::default_instance_ = NULL;
   delete OneofOptions_reflection_;
+  OneofOptions_reflection_ = NULL;
   delete EnumOptions::default_instance_;
+  EnumOptions::default_instance_ = NULL;
   delete EnumOptions_reflection_;
+  EnumOptions_reflection_ = NULL;
   delete EnumValueOptions::default_instance_;
+  EnumValueOptions::default_instance_ = NULL;
   delete EnumValueOptions_reflection_;
+  EnumValueOptions_reflection_ = NULL;
   delete ServiceOptions::default_instance_;
+  ServiceOptions::default_instance_ = NULL;
   delete ServiceOptions_reflection_;
+  ServiceOptions_reflection_ = NULL;
   delete MethodOptions::default_instance_;
+  MethodOptions::default_instance_ = NULL;
   delete MethodOptions_reflection_;
+  MethodOptions_reflection_ = NULL;
   delete UninterpretedOption::default_instance_;
+  UninterpretedOption::default_instance_ = NULL;
   delete UninterpretedOption_reflection_;
+  UninterpretedOption_reflection_ = NULL;
   delete UninterpretedOption_NamePart::default_instance_;
+  UninterpretedOption_NamePart::default_instance_ = NULL;
   delete UninterpretedOption_NamePart_reflection_;
+  UninterpretedOption_NamePart_reflection_ = NULL;
   delete SourceCodeInfo::default_instance_;
+  SourceCodeInfo::default_instance_ = NULL;
   delete SourceCodeInfo_reflection_;
+  SourceCodeInfo_reflection_ = NULL;
   delete SourceCodeInfo_Location::default_instance_;
+  SourceCodeInfo_Location::default_instance_ = NULL;
   delete SourceCodeInfo_Location_reflection_;
+  SourceCodeInfo_Location_reflection_ = NULL;
   delete GeneratedCodeInfo::default_instance_;
+  GeneratedCodeInfo::default_instance_ = NULL;
   delete GeneratedCodeInfo_reflection_;
+  GeneratedCodeInfo_reflection_ = NULL;
   delete GeneratedCodeInfo_Annotation::default_instance_;
+  GeneratedCodeInfo_Annotation::default_instance_ = NULL;
   delete GeneratedCodeInfo_Annotation_reflection_;
+  GeneratedCodeInfo_Annotation_reflection_ = NULL;
 }
-
 void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() GOOGLE_ATTRIBUTE_COLD;
 void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() {
   static bool already_here = false;