diff --git a/components/script/dom/dedicatedworkerglobalscope.rs b/components/script/dom/dedicatedworkerglobalscope.rs
index 295b0029cb3..d658163c233 100644
--- a/components/script/dom/dedicatedworkerglobalscope.rs
+++ b/components/script/dom/dedicatedworkerglobalscope.rs
@@ -240,7 +240,7 @@ impl DedicatedWorkerGlobalScope {
                 }
             };
 
-            let runtime = unsafe { new_rt_and_cx(parent_rt.rt()) };
+            let runtime = unsafe { new_rt_and_cx() };
             *worker_rt_for_mainthread.lock().unwrap() = Some(SharedRt::new(&runtime));
 
             let (devtools_mpsc_chan, devtools_mpsc_port) = channel();
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index 2b2e2437e16..543574ccc62 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -95,9 +95,9 @@ impl<'a> Drop for StackRootTLS<'a> {
 }
 
 #[allow(unsafe_code)]
-pub unsafe fn new_rt_and_cx(parent_rt: *mut JSRuntime) -> Runtime {
+pub unsafe fn new_rt_and_cx() -> Runtime {
     LiveDOMReferences::initialize();
-    let runtime = Runtime::new(parent_rt);
+    let runtime = Runtime::new();
 
     JS_AddExtraGCRootsTracer(runtime.rt(), Some(trace_rust_roots), ptr::null_mut());
     JS_AddExtraGCRootsTracer(runtime.rt(), Some(trace_refcounted_objects), ptr::null_mut());
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index a1e563d23d1..20a8602a249 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -521,7 +521,7 @@ impl ScriptThread {
                port: Receiver<MainThreadScriptMsg>,
                chan: Sender<MainThreadScriptMsg>)
                -> ScriptThread {
-        let runtime = unsafe { new_rt_and_cx(ptr::null_mut()) };
+        let runtime = unsafe { new_rt_and_cx() };
 
         unsafe {
             JS_SetWrapObjectCallbacks(runtime.rt(),
diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 2a12a2d75d7..53875b3957c 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -1079,9 +1079,10 @@ dependencies = [
 [[package]]
 name = "js"
 version = "0.1.3"
-source = "git+https://github.com/servo/rust-mozjs#fae7efd0adf42c0dde517382b83734525e11c6cc"
+source = "git+https://github.com/servo/rust-mozjs#c6f6817a7beb7f310050e1dde88654a95de6df26"
 dependencies = [
  "heapsize 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozjs_sys 0.0.0 (git+https://github.com/servo/mozjs)",
diff --git a/ports/cef/Cargo.lock b/ports/cef/Cargo.lock
index 29e487441b7..9029fa2cbfd 100644
--- a/ports/cef/Cargo.lock
+++ b/ports/cef/Cargo.lock
@@ -991,9 +991,10 @@ dependencies = [
 [[package]]
 name = "js"
 version = "0.1.3"
-source = "git+https://github.com/servo/rust-mozjs#fae7efd0adf42c0dde517382b83734525e11c6cc"
+source = "git+https://github.com/servo/rust-mozjs#c6f6817a7beb7f310050e1dde88654a95de6df26"
 dependencies = [
  "heapsize 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozjs_sys 0.0.0 (git+https://github.com/servo/mozjs)",