--- a/js/src/jit/Ion.cpp
+++ b/js/src/jit/Ion.cpp
@@ -444,24 +444,27 @@ JitCompartment::notifyOfActiveParallelEn
     // already in the set.
     if (script->parallelIonScript()->isParallelEntryScript()) {
         MOZ_ASSERT(activeParallelEntryScripts_ && activeParallelEntryScripts_->has(script));
         script->parallelIonScript()->resetParallelAge();
         return true;
     }
 
     if (!activeParallelEntryScripts_) {
-        activeParallelEntryScripts_ = cx->new_<ScriptSet>(cx);
-        if (!activeParallelEntryScripts_ || !activeParallelEntryScripts_->init())
+        ScriptSet *scripts = js_new<ScriptSet>();
+        if (!scripts || !scripts->init()) {
+            js_delete(scripts);
+            js_ReportOutOfMemory(cx);
             return false;
+        }
+        activeParallelEntryScripts_ = scripts;
     }
 
     script->parallelIonScript()->setIsParallelEntryScript();
-    ScriptSet::AddPtr p = activeParallelEntryScripts_->lookupForAdd(script);
-    return p || activeParallelEntryScripts_->add(p, script);
+    return activeParallelEntryScripts_->put(script);
 }
 
 bool
 JitCompartment::hasRecentParallelActivity() const
 {
     return activeParallelEntryScripts_ && !activeParallelEntryScripts_->empty();
 }
 

--- a/js/src/jit/JitCompartment.h
+++ b/js/src/jit/JitCompartment.h
@@ -457,17 +457,18 @@ class JitCompartment
     JitCode *stringConcatStub_;
     JitCode *parallelStringConcatStub_;
     JitCode *regExpExecStub_;
     JitCode *regExpTestStub_;
 
     // Set of JSScripts invoked by ForkJoin (i.e. the entry script). These
     // scripts are marked if their respective parallel IonScripts' age is less
     // than a certain amount. See IonScript::parallelAge_.
-    typedef HashSet<PreBarrieredScript> ScriptSet;
+    typedef HashSet<PreBarrieredScript, DefaultHasher<PreBarrieredScript>, SystemAllocPolicy>
+        ScriptSet;
     ScriptSet *activeParallelEntryScripts_;
 
     JitCode *generateStringConcatStub(JSContext *cx, ExecutionMode mode);
     JitCode *generateRegExpExecStub(JSContext *cx);
     JitCode *generateRegExpTestStub(JSContext *cx);
 
   public:
     JitCode *getStubCode(uint32_t key) {