diff --git a/js/src/jsarray.c b/js/src/jsarray.c
index 934647cb96cd..28dd426ea59b 100644
--- a/js/src/jsarray.c
+++ b/js/src/jsarray.c
@@ -2390,8 +2390,11 @@ array_concat(JSContext *cx, uintN argc, jsval *vp)
             goto out;
         v = argv[i];
         if (JSVAL_IS_OBJECT(v)) {
+            JSObject *wobj;
+
             aobj = JSVAL_TO_OBJECT(v);
-            if (aobj && OBJ_IS_ARRAY(cx, aobj)) {
+            wobj = js_GetWrappedObject(cx, aobj);
+            if (aobj && OBJ_IS_ARRAY(cx, wobj)) {
                 ok = OBJ_GET_PROPERTY(cx, aobj,
                                       ATOM_TO_JSID(cx->runtime->atomState
                                                    .lengthAtom),
diff --git a/js/src/jsgc.c b/js/src/jsgc.c
index 46411b92a964..077a9183e5d3 100644
--- a/js/src/jsgc.c
+++ b/js/src/jsgc.c
@@ -2874,17 +2874,7 @@ ProcessSetSlotRequest(JSContext *cx, JSSetSlotRequest *ssr)
     slot = ssr->slot;
 
     while (pobj) {
-        JSClass *clasp = STOBJ_GET_CLASS(pobj);
-        if (clasp->flags & JSCLASS_IS_EXTENDED) {
-            JSExtendedClass *xclasp = (JSExtendedClass *) clasp;
-            if (xclasp->wrappedObject) {
-                /* If there is no wrapped object, use the wrapper. */
-                JSObject *wrapped = xclasp->wrappedObject(cx, pobj);
-                if (wrapped)
-                    pobj = wrapped;
-            }
-        }
-
+        pobj = js_GetWrappedObject(cx, pobj);
         if (pobj == obj) {
             ssr->errnum = JSMSG_CYCLIC_VALUE;
             return;
diff --git a/js/src/jsinterp.c b/js/src/jsinterp.c
index 873e91fdde04..4861296f6e96 100644
--- a/js/src/jsinterp.c
+++ b/js/src/jsinterp.c
@@ -1769,26 +1769,11 @@ js_StrictlyEqual(JSContext *cx, jsval lval, jsval rval)
             !JSVAL_IS_NULL(lval) &&
             !JSVAL_IS_NULL(rval)) {
             JSObject *lobj, *robj;
-            JSClass *lclasp, *rclasp;
 
-            lobj = JSVAL_TO_OBJECT(lval);
-            robj = JSVAL_TO_OBJECT(rval);
-            lclasp = OBJ_GET_CLASS(cx, lobj);
-            rclasp = OBJ_GET_CLASS(cx, robj);
-            if (lclasp->flags & JSCLASS_IS_EXTENDED) {
-                JSExtendedClass *xclasp = (JSExtendedClass *) lclasp;
-                if (xclasp->wrappedObject &&
-                    (lobj = xclasp->wrappedObject(cx, lobj))) {
-                    lval = OBJECT_TO_JSVAL(lobj);
-                }
-            }
-            if (rclasp->flags & JSCLASS_IS_EXTENDED) {
-                JSExtendedClass *xclasp = (JSExtendedClass *) rclasp;
-                if (xclasp->wrappedObject &&
-                    (robj = xclasp->wrappedObject(cx, robj))) {
-                    rval = OBJECT_TO_JSVAL(robj);
-                }
-            }
+            lobj = js_GetWrappedObject(cx, JSVAL_TO_OBJECT(lval));
+            robj = js_GetWrappedObject(cx, JSVAL_TO_OBJECT(rval));
+            lval = OBJECT_TO_JSVAL(lobj);
+            rval = OBJECT_TO_JSVAL(robj);
         }
         return lval == rval;
     }
diff --git a/js/src/jsobj.c b/js/src/jsobj.c
index f1f5e8f21628..c2541ea525ec 100644
--- a/js/src/jsobj.c
+++ b/js/src/jsobj.c
@@ -1010,25 +1010,14 @@ obj_toString(JSContext *cx, uintN argc, jsval *vp)
     JSObject *obj;
     jschar *chars;
     size_t nchars;
-    JSClass *clasp;
     const char *clazz, *prefix;
     JSString *str;
 
     obj = JS_THIS_OBJECT(cx, vp);
     if (!obj)
         return JS_FALSE;
-    clasp = OBJ_GET_CLASS(cx, obj);
-    if (clasp->flags & JSCLASS_IS_EXTENDED) {
-        JSExtendedClass *xclasp;
-        JSObject *obj2;
-
-        if ((xclasp = (JSExtendedClass *)clasp)->wrappedObject &&
-            (obj2 = xclasp->wrappedObject(cx, obj))) {
-            obj = obj2;
-            clasp = OBJ_GET_CLASS(cx, obj);
-        }
-    }
-    clazz = clasp->name;
+    obj = js_GetWrappedObject(cx, obj);
+    clazz = OBJ_GET_CLASS(cx, obj)->name;
     nchars = 9 + strlen(clazz);         /* 9 for "[object ]" */
     chars = (jschar *) JS_malloc(cx, (nchars + 1) * sizeof(jschar));
     if (!chars)
@@ -1174,16 +1163,10 @@ obj_eval(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
      * the former indirect case.
      */
     scopeobj = OBJ_GET_PARENT(cx, obj);
-    if (scopeobj &&
-        ((clasp = OBJ_GET_CLASS(cx, obj))->flags & JSCLASS_IS_EXTENDED)) {
-        JSExtendedClass *xclasp = (JSExtendedClass *) clasp;
-        if (xclasp->wrappedObject) {
-            JSObject *wrapped = xclasp->wrappedObject(cx, obj);
-            if (wrapped)
-                scopeobj = OBJ_GET_PARENT(cx, wrapped);
-        }
+    if (scopeobj) {
+        scopeobj = js_GetWrappedObject(cx, obj);
+        scopeobj = OBJ_GET_PARENT(cx, scopeobj);
     }
-
     if (indirectCall || scopeobj) {
         uintN flags = scopeobj
                       ? JSREPORT_ERROR
@@ -5120,6 +5103,23 @@ js_SetRequiredSlot(JSContext *cx, JSObject *obj, uint32 slot, jsval v)
     return JS_TRUE;
 }
 
+JSObject *
+js_GetWrappedObject(JSContext *cx, JSObject *obj)
+{
+    JSClass *clasp;
+
+    clasp = OBJ_GET_CLASS(cx, obj);
+    if (clasp->flags & JSCLASS_IS_EXTENDED) {
+        JSExtendedClass *xclasp;
+        JSObject *obj2;
+
+        xclasp = (JSExtendedClass *)clasp;
+        if (xclasp->wrappedObject && (obj2 = xclasp->wrappedObject(cx, obj)))
+            return obj2;
+    }
+    return obj;
+}
+
 #ifdef DEBUG
 
 /* Routines to print out values during debugging. */
diff --git a/js/src/jsobj.h b/js/src/jsobj.h
index b262602339b9..ba7506eb23a3 100644
--- a/js/src/jsobj.h
+++ b/js/src/jsobj.h
@@ -695,6 +695,10 @@ extern JSBool
 js_CheckPrincipalsAccess(JSContext *cx, JSObject *scopeobj,
                          JSPrincipals *principals, JSAtom *caller);
 
+/* Infallible -- returns its argument if there is no wrapped object. */
+extern JSObject *
+js_GetWrappedObject(JSContext *cx, JSObject *obj);
+
 JS_END_EXTERN_C
 
 #endif /* jsobj_h___ */