diff --git a/ssl/ssl3con.c b/ssl/ssl3con.c
index a67a9d1..02b0dda 100644
--- a/ssl/ssl3con.c
+++ b/ssl/ssl3con.c
@@ -6964,7 +6964,8 @@ ssl3_HandleServerKeyExchange(sslSocket *ss, SSL3Opaque *b, PRUint32 length)
     	if (rv != SECSuccess) {
 	    goto loser;		/* malformed. */
 	}
-	if (dh_p.len < 512/8) {
+	if (dh_p.len < 1024/8 ||
+	    (dh_p.len == 1024/8 && (dh_p.data[0] & 0x80) == 0)) {
 	    errCode = SSL_ERROR_WEAK_SERVER_EPHEMERAL_DH_KEY;
 	    goto alert_loser;
 	}