diff --git a/mozilla/xpcom/reflect/xptinfo/src/xptiInterfaceInfo.cpp b/mozilla/xpcom/reflect/xptinfo/src/xptiInterfaceInfo.cpp
index 53794c7266a..030566a20df 100644
--- a/mozilla/xpcom/reflect/xptinfo/src/xptiInterfaceInfo.cpp
+++ b/mozilla/xpcom/reflect/xptinfo/src/xptiInterfaceInfo.cpp
@@ -82,6 +82,19 @@ xptiInterfaceInfo::~xptiInterfaceInfo()
         delete mInterface;        
 }        
 
+void 
+xptiInterfaceInfo::Invalidate()
+{ 
+    if(IsValid())
+    {
+        // The order of operations here is important!
+        xptiTypelib typelib = GetTypelibRecord();
+        if(HasInterfaceRecord())
+            delete mInterface;        
+        mTypelib = typelib;
+        mName = nsnull;
+    }
+}
 
 PRBool 
 xptiInterfaceInfo::Resolve(xptiWorkingSet* aWorkingSet /* = nsnull */)
diff --git a/mozilla/xpcom/reflect/xptinfo/src/xptiprivate.h b/mozilla/xpcom/reflect/xptinfo/src/xptiprivate.h
index e8de024c421..422c7a25b4f 100644
--- a/mozilla/xpcom/reflect/xptinfo/src/xptiprivate.h
+++ b/mozilla/xpcom/reflect/xptinfo/src/xptiprivate.h
@@ -487,15 +487,7 @@ public:
     PRBool PartiallyResolveLocked(XPTInterfaceDescriptor*  aDescriptor,
                                   xptiWorkingSet*          aWorkingSet);
 
-    void Invalidate()
-        { 
-            if(IsValid())
-            {
-                xptiTypelib typelib = GetTypelibRecord();
-                mTypelib = typelib;
-                mName = nsnull;
-            }
-        }
+    void Invalidate();
 
 private:
     void CopyName(const char* name,