diff --git a/contrib/pgcrypto/pgp-compress.c b/contrib/pgcrypto/pgp-compress.c
index 0505bdee923..4b1d2a1ff5f 100644
--- a/contrib/pgcrypto/pgp-compress.c
+++ b/contrib/pgcrypto/pgp-compress.c
@@ -114,13 +114,13 @@ compress_process(PushFilter *next, void *priv, const uint8 *data, int len)
 	/*
 	 * process data
 	 */
-	while (len > 0)
+	st->stream.next_in = unconstify(uint8 *, data);
+	st->stream.avail_in = len;
+	while (st->stream.avail_in > 0)
 	{
-		st->stream.next_in = unconstify(uint8 *, data);
-		st->stream.avail_in = len;
 		st->stream.next_out = st->buf;
 		st->stream.avail_out = st->buf_len;
-		res = deflate(&st->stream, 0);
+		res = deflate(&st->stream, Z_NO_FLUSH);
 		if (res != Z_OK)
 			return PXE_PGP_COMPRESSION_ERROR;
 
@@ -131,7 +131,6 @@ compress_process(PushFilter *next, void *priv, const uint8 *data, int len)
 			if (res < 0)
 				return res;
 		}
-		len = st->stream.avail_in;
 	}
 
 	return 0;
@@ -154,6 +153,7 @@ compress_flush(PushFilter *next, void *priv)
 		zres = deflate(&st->stream, Z_FINISH);
 		if (zres != Z_STREAM_END && zres != Z_OK)
 			return PXE_PGP_COMPRESSION_ERROR;
+
 		n_out = st->buf_len - st->stream.avail_out;
 		if (n_out > 0)
 		{