diff --git a/tests/threads.cpp b/tests/threads.cpp
index b8c0e6620..63c31200a 100644
--- a/tests/threads.cpp
+++ b/tests/threads.cpp
@@ -9,19 +9,19 @@ BOOST_AUTO_TEST_CASE(threads)
 {
     const size_t n = 1024 * 1024;
 
-    auto run = [n](vex::backend::command_queue queue, cl_long &s) {
+    auto run = [n](vex::backend::command_queue queue, cl_long *s) {
         std::vector<vex::backend::command_queue> q(1, queue);
         vex::vector<int> x(q, n);
         x = 1;
         vex::Reductor<cl_long, vex::SUM> sum(q);
-        s = sum(x);
+        *s = sum(x);
     };
 
     std::vector< boost::thread > threads;
     std::vector< cl_long       > results(ctx.size(), 0);
 
     for(unsigned d = 0; d < ctx.size(); ++d) {
-        threads.push_back( boost::thread(run, ctx.queue(d), results[d]) );
+        threads.push_back( boost::thread(run, ctx.queue(d), &results[d]) );
     }
 
     cl_long sum = 0;