diff --git a/uriloader/exthandler/unix/nsOSHelperAppService.cpp b/uriloader/exthandler/unix/nsOSHelperAppService.cpp

--- a/uriloader/exthandler/unix/nsOSHelperAppService.cpp

+++ b/uriloader/exthandler/unix/nsOSHelperAppService.cpp

@@ -1620,23 +1620,19 @@ nsOSHelperAppService::GetMIMEInfoFromOS(

   PRBool hasDefault = PR_FALSE;

   if (retval)

     retval->GetHasDefaultHandler(&hasDefault);

   if (!retval || !hasDefault) {

     nsRefPtr<nsMIMEInfoBase> miByExt = GetFromExtension(PromiseFlatCString(aFileExt));

     // If we had no extension match, but a type match, use that

     if (!miByExt && retval)

       return retval;

-    // If we had an extension match but no type match, set the mimetype and use

-    // it

+    // If we had an extension match but no type match, use it

     if (!retval && miByExt) {

-      if (!aType.IsEmpty())

-        miByExt->SetMIMEType(aType);

       miByExt.swap(retval);

-

       return retval;

     }

     // If we got nothing, make a new mimeinfo

     if (!retval) {

       *aFound = PR_FALSE;

       retval = new nsMIMEInfoUnix(aType);

       if (retval) {

         NS_ADDREF(retval);