--- a/js/src/jsemit.cpp
+++ b/js/src/jsemit.cpp
@@ -1871,18 +1871,17 @@ BindNameToSlot(JSContext *cx, JSCodeGene
     /*
      * We can't optimize if var and closure (a local function not in a larger
      * expression and not at top-level within another's body) collide.
      * XXX suboptimal: keep track of colliding names and deoptimize only those
      */
     if (tc->flags & TCF_FUN_CLOSURE_VS_VAR)
         return JS_TRUE;
 
-    /* Don't generate upvars on the left side of a for loop. See bug 470758. */
-    if (!(tc->flags & (TCF_IN_FUNCTION | TCF_IN_FOR_INIT))) {
+    if (!(tc->flags & TCF_IN_FUNCTION)) {
         JSStackFrame *caller;
 
         caller = tc->parseContext->callerFrame;
         if (caller) {
             JS_ASSERT(tc->flags & TCF_COMPILE_N_GO);
             JS_ASSERT(caller->script);
             if (!caller->fun || caller->varobj != tc->u.scopeChain)
                 return JS_TRUE;
@@ -1894,16 +1893,23 @@ BindNameToSlot(JSContext *cx, JSCodeGene
              * arguments object.
              */
             if (PN_OP(pn) != JSOP_NAME || cg->staticDepth > JS_DISPLAY_SIZE)
                 goto arguments_check;
             localKind = js_LookupLocal(cx, caller->fun, atom, &index);
             if (localKind == JSLOCAL_NONE)
                 goto arguments_check;
 
+            /*
+             * Don't generate upvars on the left side of a for loop. See
+             * bug 470758.
+             */
+            if (tc->flags & TCF_IN_FOR_INIT)
+                goto arguments_check;
+
             ATOM_LIST_SEARCH(ale, &cg->upvarList, atom);
             if (!ale) {
                 uint32 length, *vector;
 
                 ale = js_IndexAtom(cx, atom, &cg->upvarList);
                 if (!ale)
                     return JS_FALSE;
                 JS_ASSERT(ALE_INDEX(ale) == cg->upvarList.count - 1);