diff --git a/js/src/methodjit/Compiler.cpp b/js/src/methodjit/Compiler.cpp
index 7fac7f69688..6a942938b24 100644
--- a/js/src/methodjit/Compiler.cpp
+++ b/js/src/methodjit/Compiler.cpp
@@ -910,6 +910,7 @@ mjit::Compiler::generateMethod()
 
           BEGIN_CASE(JSOP_EXCEPTION)
           {
+            JS_STATIC_ASSERT(sizeof(cx->throwing) == 4);
             RegisterID reg = frame.allocReg();
             masm.loadPtr(FrameAddress(offsetof(VMFrame, cx)), reg);
             masm.store32(Imm32(JS_FALSE), Address(reg, offsetof(JSContext, throwing)));
diff --git a/js/src/methodjit/StubCalls.cpp b/js/src/methodjit/StubCalls.cpp
index 990f17152e9..8be70cacc9c 100644
--- a/js/src/methodjit/StubCalls.cpp
+++ b/js/src/methodjit/StubCalls.cpp
@@ -2517,7 +2517,6 @@ stubs::ArgCnt(VMFrame &f)
 void JS_FASTCALL
 stubs::EnterBlock(VMFrame &f, JSObject *obj)
 {
-    JSContext *cx = f.cx;
     JSFrameRegs &regs = f.regs;
     JSStackFrame *fp = f.fp;
 
@@ -2530,6 +2529,7 @@ stubs::EnterBlock(VMFrame &f, JSObject *obj)
     regs.sp = vp;
 
 #ifdef DEBUG
+    JSContext *cx = f.cx;
     JS_ASSERT(fp->blockChain == obj->getParent());
 
     /*