diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index ac5e7939e24f..c7231c3f5669 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -432,7 +432,7 @@ public:
   {
     if (mInstance && mPluginHost) {
       nsCOMPtr<nsPIPluginHost> piPluginHost = do_QueryInterface(mPluginHost);
-      char* name = NULL;
+      const char* name = NULL;
       if (NS_SUCCEEDED(piPluginHost->GetPluginName(mInstance, &name)) &&
           name)
         return name;
diff --git a/modules/plugin/base/public/nsPIPluginHost.idl b/modules/plugin/base/public/nsPIPluginHost.idl
index daa948ae28f4..b102f4f4a587 100644
--- a/modules/plugin/base/public/nsPIPluginHost.idl
+++ b/modules/plugin/base/public/nsPIPluginHost.idl
@@ -46,7 +46,7 @@ interface nsIPluginInstanceOwner;
 
 [ptr] native nsPluginNativeWindowPtr(nsPluginNativeWindow);
 
-[uuid(75d8fcd7-06d1-4767-9022-7f8dacf48a68)]
+[uuid(673811fb-83d6-4b8f-b1a9-bb3a9033f256)]
 interface nsPIPluginHost : nsISupports
 {
  /**
@@ -106,6 +106,10 @@ interface nsPIPluginHost : nsISupports
 
  /**
   * Get the plugin name for the plugin instance.
+  * @param aInstance the plugin instance object
+  * @param aPluginName returns a pointer to a shared readonly string value,
+  *        it's only valid for the lifetime of the plugin instance - you must
+  *        copy the string value if you need it longer than that.
   */
-  [noscript] void getPluginName(in nsIPluginInstance aInstance, out string aPluginName);
+  [noscript] void getPluginName(in nsIPluginInstance aInstance, [shared] out string aPluginName);
 };
diff --git a/modules/plugin/base/src/nsPluginHostImpl.cpp b/modules/plugin/base/src/nsPluginHostImpl.cpp
index a315fad0d134..205b986a7081 100644
--- a/modules/plugin/base/src/nsPluginHostImpl.cpp
+++ b/modules/plugin/base/src/nsPluginHostImpl.cpp
@@ -6930,9 +6930,9 @@ nsPluginHostImpl::InstantiateDummyJavaPlugin(nsIPluginInstanceOwner *aOwner)
 
 NS_IMETHODIMP
 nsPluginHostImpl::GetPluginName(nsIPluginInstance *aPluginInstance,
-                                char** aPluginName)
+                                const char** aPluginName)
 {
-  *aPluginName = (char*)GetPluginName(aPluginInstance);
+  *aPluginName = GetPluginName(aPluginInstance);
   return NS_OK;
 }