diff --git a/pcapng/structs.py b/pcapng/structs.py
index 65e5969..57f5890 100644
--- a/pcapng/structs.py
+++ b/pcapng/structs.py
@@ -906,7 +906,7 @@ def _decode_value(self, value, ftype):
         if ftype == TYPE_IPV6_PREFIX:
             return (
                 unpack_ipv6(value[:16]),
-                struct.unpack(self.endianness + "B", value[16]),
+                value[16]
             )
 
         if ftype == TYPE_MACADDR: