First foray into c++ land - getting node: malloc(): memory corruptio

binding.gyp

{
  "targets": [
    {
      "target_name": "wkhtmltox",
      "sources": [ "wkhtmltox-google.cpp" ],
      "include_dirs": ["/include"],
      "libraries": ["-lwkhtmltox"]
    }
  ]
}

wkhtmltox-google.cpp

#include <node.h>
#include <wkhtmltox/pdf.h>

using namespace v8;

Handle<Value> Pdf(const Arguments& args) {
    HandleScope scope;

    Local<Function> callback = Local<Function>::Cast(args[0]);

    wkhtmltopdf_init(0);
    wkhtmltopdf_global_settings *global_settings = wkhtmltopdf_create_global_settings();
    wkhtmltopdf_set_global_setting(global_settings, "out", "google.pdf");
    wkhtmltopdf_converter *c = wkhtmltopdf_create_converter(global_settings);

    wkhtmltopdf_object_settings *object_settings = wkhtmltopdf_create_object_settings();
    wkhtmltopdf_set_object_setting(object_settings, "page", "www.google.com");
    wkhtmltopdf_add_object(c, object_settings, NULL);
    wkhtmltopdf_convert(c);

    const unsigned argc = 3;
    Local<Value> argv[argc] = {
        Local<Value>::New(Null()),
        Local<Value>::New(Integer::New(0)),
        Local<Value>::New(String::New(wkhtmltopdf_version()))
    };

    callback->Call(Context::GetCurrent()->Global(), argc, argv);

    return Undefined();
}

void RegisterModule(Handle<Object> target) {
    target->Set(String::NewSymbol("pdf"),
        FunctionTemplate::New(Pdf)->GetFunction());
}

NODE_MODULE(wkhtmltox, RegisterModule);