diff --git a/js/src/jsapi-tests/testThreadingExclusiveData.cpp b/js/src/jsapi-tests/testThreadingExclusiveData.cpp
index 1e8ec68ad9ce..04b16031b5c7 100644
--- a/js/src/jsapi-tests/testThreadingExclusiveData.cpp
+++ b/js/src/jsapi-tests/testThreadingExclusiveData.cpp
@@ -8,6 +8,7 @@
 #include "js/Vector.h"
 #include "jsapi-tests/tests.h"
 #include "threading/ExclusiveData.h"
+#include "threading/Thread.h"
 
 // One thread for each bit in our counter.
 const static uint8_t NumThreads = 64;
@@ -43,10 +44,8 @@ printDiagnosticMessage(uint64_t seen)
 }
 
 void
-setBitAndCheck(void* arg)
+setBitAndCheck(CounterAndBit& counterAndBit)
 {
-    auto& counterAndBit = *static_cast<CounterAndBit*>(arg);
-
     while (true) {
         {
             // Set our bit. Repeatedly setting it is idempotent.
@@ -72,26 +71,17 @@ BEGIN_TEST(testExclusiveData)
 {
     js::ExclusiveData<uint64_t> counter(0);
 
-    js::Vector<PRThread*> threads(cx);
+    js::Vector<js::Thread> threads(cx);
     CHECK(threads.reserve(NumThreads));
 
     for (auto i : mozilla::MakeRange(NumThreads)) {
         auto counterAndBit = js_new<CounterAndBit>(i, counter);
         CHECK(counterAndBit);
-        auto thread = PR_CreateThread(PR_USER_THREAD,
-                                      setBitAndCheck,
-                                      (void *) counterAndBit,
-                                      PR_PRIORITY_NORMAL,
-                                      PR_LOCAL_THREAD,
-                                      PR_JOINABLE_THREAD,
-                                      0);
-        CHECK(thread);
-        threads.infallibleAppend(thread);
+        CHECK(threads.emplaceBack(setBitAndCheck, *counterAndBit));
     }
 
-    for (auto thread : threads) {
-        CHECK(PR_JoinThread(thread) == PR_SUCCESS);
-    }
+    for (auto& thread : threads)
+        thread.join();
 
     return true;
 }