diff -ruN postgresql-7.4.8-old/src/interfaces/libpq/fe-auth.c postgresql-7.4.8/src/interfaces/libpq/fe-auth.c
--- postgresql-7.4.8-old/src/interfaces/libpq/fe-auth.c	2003-12-20 19:46:02.000000000 +0100
+++ postgresql-7.4.8/src/interfaces/libpq/fe-auth.c	2005-08-14 13:34:23.000000000 +0200
@@ -366,6 +366,12 @@
 	krb5_error *err_ret = NULL;
 	int			flags;
 
+        if (!hostname) {
+		snprintf(PQerrormsg, INITIAL_EXPBUFFER_SIZE,
+				 "pg_krb5_sendauth: hostname must be specified for kerberos authentication\n");
+		return STATUS_ERROR;
+	}
+
 	ret = pg_krb5_init(PQerrormsg);
 	if (ret != STATUS_OK)
 		return ret;