diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
index 0291ef814aa..872262aa46f 100644
--- a/js/src/jsobj.cpp
+++ b/js/src/jsobj.cpp
@@ -2450,15 +2450,14 @@ unsigned
 js_InferFlags(JSContext *cx, unsigned defaultFlags)
 {
     /*
-     * Use ScriptFrameIter since we intentionally want to look across
-     * compartment boundaries in the case of cross-compartment property access.
+     * We intentionally want to look across compartment boundaries to correctly
+     * handle the case of cross-compartment property access.
      */
-    ScriptFrameIter i(cx);
-    if (i.done())
+    jsbytecode *pc;
+    JSScript *script = cx->stack.currentScript(&pc, ContextStack::ALLOW_CROSS_COMPARTMENT);
+    if (!script)
         return defaultFlags;
 
-    jsbytecode *pc = i.pc();
-    JSScript *script = i.script();
     const JSCodeSpec *cs = &js_CodeSpec[*pc];
     uint32_t format = cs->format;
     unsigned flags = 0;
diff --git a/js/src/vm/Stack-inl.h b/js/src/vm/Stack-inl.h
index 7304799f202..559a3cc3c50 100644
--- a/js/src/vm/Stack-inl.h
+++ b/js/src/vm/Stack-inl.h
@@ -516,7 +516,8 @@ ContextStack::popFrameAfterOverflow()
 }
 
 inline JSScript *
-ContextStack::currentScript(jsbytecode **ppc) const
+ContextStack::currentScript(jsbytecode **ppc,
+                            MaybeAllowCrossCompartment allowCrossCompartment) const
 {
     if (ppc)
         *ppc = NULL;
@@ -531,7 +532,7 @@ ContextStack::currentScript(jsbytecode **ppc) const
     if (fp->beginsIonActivation()) {
         JSScript *script = NULL;
         ion::GetPcScript(cx_, &script, ppc);
-        if (script->compartment() != cx_->compartment)
+        if (!allowCrossCompartment && script->compartment() != cx_->compartment)
             return NULL;
         return script;
     }
@@ -544,7 +545,7 @@ ContextStack::currentScript(jsbytecode **ppc) const
         JS_ASSERT(inlined->inlineIndex < chunk->nInlineFrames);
         mjit::InlineFrame *frame = &chunk->inlineFrames()[inlined->inlineIndex];
         JSScript *script = frame->fun->script();
-        if (script->compartment() != cx_->compartment)
+        if (!allowCrossCompartment && script->compartment() != cx_->compartment)
             return NULL;
         if (ppc)
             *ppc = script->code + inlined->pcOffset;
@@ -553,7 +554,7 @@ ContextStack::currentScript(jsbytecode **ppc) const
 #endif
 
     JSScript *script = fp->script();
-    if (script->compartment() != cx_->compartment)
+    if (!allowCrossCompartment && script->compartment() != cx_->compartment)
         return NULL;
 
     if (ppc)
diff --git a/js/src/vm/Stack.h b/js/src/vm/Stack.h
index 3ede461919c..5a646b758bf 100644
--- a/js/src/vm/Stack.h
+++ b/js/src/vm/Stack.h
@@ -1588,8 +1588,18 @@ class ContextStack
     /* Pop a partially-pushed frame after hitting the limit before throwing. */
     void popFrameAfterOverflow();
 
-    /* Get the topmost script and optional pc on the stack. */
-    inline JSScript *currentScript(jsbytecode **pc = NULL) const;
+    /*
+     * Get the topmost script and optional pc on the stack. By default, this
+     * function only returns a JSScript in the current compartment, returning
+     * NULL if the current script is in a different compartment. This behavior
+     * can be overridden by passing ALLOW_CROSS_COMPARTMENT.
+     */
+    enum MaybeAllowCrossCompartment {
+        DONT_ALLOW_CROSS_COMPARTMENT = false,
+        ALLOW_CROSS_COMPARTMENT = true
+    };
+    inline JSScript *currentScript(jsbytecode **pc = NULL,
+                                   MaybeAllowCrossCompartment = DONT_ALLOW_CROSS_COMPARTMENT) const;
 
     /* Get the scope chain for the topmost scripted call on the stack. */
     inline HandleObject currentScriptedScopeChain() const;