Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 87651)
+++ channels/chan_sip.c	(working copy)
@@ -17490,7 +17490,7 @@
 
 		strsep(&context, "@");
 		if (ast_strlen_zero(mbox)) {
-			free(mailbox);
+			ast_free(mailbox);
 			continue;
 		}
 		mailbox->mailbox = ast_strdup(mbox);