diff --git a/Source/WebCore/bindings/js/SerializedScriptValue.cpp b/Source/WebCore/bindings/js/SerializedScriptValue.cpp
index b3d07ca..6c69cc2 100644
--- a/Source/WebCore/bindings/js/SerializedScriptValue.cpp
+++ b/Source/WebCore/bindings/js/SerializedScriptValue.cpp
@@ -1176,7 +1176,9 @@
             CachedStringRef flags;
             if (!readStringData(flags))
                 return JSValue();
-            RefPtr<RegExp> regExp = RegExp::create(&m_exec->globalData(), pattern->ustring(), flags->ustring());
+            RegExpFlags reFlags = regExpFlags(flags->ustring());
+            ASSERT(reFlags != InvalidFlags);
+            RefPtr<RegExp> regExp = RegExp::create(&m_exec->globalData(), pattern->ustring(), reFlags);
             return new (m_exec) RegExpObject(m_exec->lexicalGlobalObject(), m_globalObject->regExpStructure(), regExp); 
         }
         case ObjectReferenceTag: {