--- lib/encode.c
+++ lib/encode.c
@@ -30,7 +30,7 @@
 	int i, sum = 0;
 
 	if (t->options & TAR_GNU)
-		strncpy(t->th_buf.magic, "ustar  ", 8);
+		strncpy(t->th_buf.magic, "ustar", 6);
 	else
 	{
 		strncpy(t->th_buf.version, TVERSION, TVERSLEN);