diff --git a/xpcom/base/IIDS.h b/xpcom/base/IIDS.h
index 4141024d82e5..d050098ed48f 100644
--- a/xpcom/base/IIDS.h
+++ b/xpcom/base/IIDS.h
@@ -1193,7 +1193,7 @@ nsParserService_CID = { /* a6cf9112-15b3-11d2-932e-00805f8add32 */
     0x11d2,
     {0x93, 0x2e, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32}
   };
-INTERFACENAME = { /* a6cf9113-15b3-11d2-932e-00805f8add32 */
+nsIMathMLFrame = { /* a6cf9113-15b3-11d2-932e-00805f8add32 */
     0xa6cf9113,
     0x15b3,
     0x11d2,