diff --git a/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp b/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
index 4d1914c2389..8acba414f01 100644
--- a/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
+++ b/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
@@ -1956,6 +1956,7 @@ nsPluginStreamListenerPeer::SetupPluginCacheFile(nsIChannel* channel)
       return rv;
 
     // Create a file to save our stream into. Should we scramble the name?
+    filename.Insert(NS_LITERAL_CSTRING("plugin-"), 0);
     rv = pluginTmp->AppendNative(filename);
     if (NS_FAILED(rv))
       return rv;