diff --git a/archive-tar.c b/archive-tar.c
index 53d0ef685c..efba78118b 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -463,6 +463,9 @@ static const char internal_gzip_command[] = "git archive gzip";
 static int write_tar_filter_archive(const struct archiver *ar,
 				    struct archiver_args *args)
 {
+#if ZLIB_VERNUM >= 0x1221
+	struct gz_header_s gzhead = { .os = 3 }; /* Unix, for reproducibility */
+#endif
 	struct strbuf cmd = STRBUF_INIT;
 	struct child_process filter = CHILD_PROCESS_INIT;
 	int r;
@@ -473,6 +476,10 @@ static int write_tar_filter_archive(const struct archiver *ar,
 	if (!strcmp(ar->filter_command, internal_gzip_command)) {
 		write_block = tgz_write_block;
 		git_deflate_init_gzip(&gzstream, args->compression_level);
+#if ZLIB_VERNUM >= 0x1221
+		if (deflateSetHeader(&gzstream.z, &gzhead) != Z_OK)
+			BUG("deflateSetHeader() called too late");
+#endif
 		gzstream.next_out = outbuf;
 		gzstream.avail_out = sizeof(outbuf);