--- a/js/src/jit/CodeGenerator.cpp
+++ b/js/src/jit/CodeGenerator.cpp
@@ -1856,31 +1856,31 @@ CodeGenerator::visitPostWriteBarrierO(LP
 bool
 CodeGenerator::visitPostWriteBarrierV(LPostWriteBarrierV *lir)
 {
 #ifdef JSGC_GENERATIONAL
     OutOfLineCallPostWriteBarrier *ool = new(alloc()) OutOfLineCallPostWriteBarrier(lir, lir->object());
     if (!addOutOfLineCode(ool))
         return false;
 
-    ValueOperand value = ToValue(lir, LPostWriteBarrierV::Input);
-    masm.branchTestObject(Assembler::NotEqual, value, ool->rejoin());
-
     const Nursery &nursery = GetIonContext()->runtime->gcNursery();
 
     if (lir->object()->isConstant()) {
         JS_ASSERT(!nursery.isInside(&lir->object()->toConstant()->toObject()));
     } else {
         Register temp = ToRegister(lir->temp());
         Register objreg = ToRegister(lir->object());
         masm.movePtr(ImmWord(-ptrdiff_t(nursery.start())), temp);
         masm.addPtr(objreg, temp);
         masm.branchPtr(Assembler::Below, temp, Imm32(Nursery::NurserySize), ool->rejoin());
     }
 
+    ValueOperand value = ToValue(lir, LPostWriteBarrierV::Input);
+    masm.branchTestObject(Assembler::NotEqual, value, ool->rejoin());
+
     // This section is a little different because we mustn't trash the temp
     // register before we use its contents.
     Register temp = ToRegister(lir->temp());
     masm.unboxObject(value, temp);
     masm.addPtr(ImmWord(-ptrdiff_t(nursery.start())), temp);
     masm.branchPtr(Assembler::Below, temp, Imm32(Nursery::NurserySize), ool->entry());
 
     masm.bind(ool->rejoin());