diff --git a/usr.bin/gzip/unpack.c b/usr.bin/gzip/unpack.c
index aa1480016d28..cc717a6a95eb 100644
--- a/usr.bin/gzip/unpack.c
+++ b/usr.bin/gzip/unpack.c
@@ -312,7 +312,14 @@ unpack(int in, int out, char *pre, size_t prelen, off_t *bytes_in)
 {
 	unpack_descriptor_t	unpackd;
 
-	unpack_parse_header(dup(in), dup(out), pre, prelen, bytes_in, &unpackd);
+	in = dup(in);
+	if (in == -1)
+		maybe_err("dup");
+	out = dup(out);
+	if (out == -1)
+		maybe_err("dup");
+
+	unpack_parse_header(in, out, pre, prelen, bytes_in, &unpackd);
 	unpack_decode(&unpackd, bytes_in);
 	unpack_descriptor_fini(&unpackd);