Origin: https://bugs.gentoo.org/719208
Author: Rafał Mużyło

--- a/rpmoffset.c
+++ b/rpmoffset.c
@@ -58,11 +58,13 @@ int is_magic_lzma(const char *buf)
 static const unsigned char magic_gzip[]  = { '\037', '\213', '\010' };
 static const unsigned char magic_bzip2[] = { 'B', 'Z', 'h' };
 static const unsigned char magic_xz[]    = { 0xFD, '7', 'z', 'X', 'Z', 0x00 };
+static const unsigned char magic_zstd[]  = { 0x28, 0xB5, 0x2F, 0xFD };
 static const magic_t magics[] = {
 #define DECLARE_MAGIC_T(t) { .type = #t, .magic = magic_##t, .len = sizeof(magic_##t), },
 	DECLARE_MAGIC_T(gzip)
 	DECLARE_MAGIC_T(bzip2)
 	DECLARE_MAGIC_T(xz)
+	DECLARE_MAGIC_T(zstd)
 #undef DECLARE_MAGIC_T
 };
 #define MAGIC_SIZE_MIN 3