diff -up ./Release/include/pplx/threadpool.h.orig ./Release/include/pplx/threadpool.h
--- ./Release/include/pplx/threadpool.h.orig	2018-01-02 00:00:45.072599770 +0100
+++ ./Release/include/pplx/threadpool.h	2018-01-02 00:01:04.504600576 +0100
@@ -53,7 +53,7 @@ class threadpool
 {
 public:
     static threadpool& shared_instance();
-    _ASYNCRTIMP static std::unique_ptr<threadpool> __cdecl construct(size_t num_threads);
+    _ASYNCRTIMP static std::unique_ptr<threadpool> __cdecl construct(int num_threads);
 
     virtual ~threadpool() = default;
 
@@ -67,7 +67,7 @@ public:
     boost::asio::io_service& service() { return m_service; }
 
 protected:
-    threadpool(size_t num_threads) : m_service(num_threads) {}
+    threadpool(int num_threads) : m_service(num_threads) {}
 
     boost::asio::io_service m_service;
 };
diff -up ./Release/src/pplx/threadpool.cpp.orig ./Release/src/pplx/threadpool.cpp
--- ./Release/src/pplx/threadpool.cpp.orig	2018-01-01 23:45:35.424562058 +0100
+++ ./Release/src/pplx/threadpool.cpp	2018-01-01 23:51:05.732575752 +0100
@@ -31,11 +31,11 @@ namespace
 
 struct threadpool_impl final : crossplat::threadpool
 {
-    threadpool_impl(size_t n)
+    threadpool_impl(int n)
         : crossplat::threadpool(n)
         , m_work(m_service)
     {
-        for (size_t i = 0; i < n; i++)
+        for (int i = 0; i < n; i++)
             add_thread();
     }
 
@@ -152,7 +152,7 @@ void cpprest_init(JavaVM* vm) {
 }
 #endif
 
-std::unique_ptr<crossplat::threadpool> crossplat::threadpool::construct(size_t num_threads)
+std::unique_ptr<crossplat::threadpool> crossplat::threadpool::construct(int num_threads)
 {
     return std::unique_ptr<crossplat::threadpool>(new threadpool_impl(num_threads));
 }