diff -urN evolution-exchange-2.8.3.orig/addressbook/e-book-backend-gal.c evolution-exchange-2.8.3/addressbook/e-book-backend-gal.c
--- evolution-exchange-2.8.3.orig/addressbook/e-book-backend-gal.c	2007-01-29 14:28:09.000000000 +0100
+++ evolution-exchange-2.8.3/addressbook/e-book-backend-gal.c	2007-03-06 17:09:40.000000000 +0100
@@ -334,7 +334,7 @@
 		ldap_abandon (bl->priv->ldap, op->id);
 	g_mutex_unlock (bl->priv->ldap_lock);
 
-	op->dtor (op);
+	if (op->dtor) op->dtor (op);
 
 	bl->priv->active_ops--;
 
