diff --git a/test/patches/scapy-2.4.5/ppp.patch b/test/patches/scapy-2.4.5/ppp.patch
new file mode 100644
index 0000000..a3680bf
--- /dev/null
+++ b/test/patches/scapy-2.4.5/ppp.patch
@@ -0,0 +1,45 @@
+# NOTE: This patch copied from https://github.com/secdev/scapy
+#       commit 3e6900776698cd5472c5405294414d5b672a3f18
+#
+diff --git a/scapy/layers/ppp.py b/scapy/layers/ppp.py
+index b5cd42b4..e0f4c593 100644
+--- a/scapy/layers/ppp.py
++++ b/scapy/layers/ppp.py
+@@ -292,6 +292,14 @@ class _PPPProtoField(EnumField):
+ 
+     See RFC 1661 section 2
+     <https://tools.ietf.org/html/rfc1661#section-2>
++
++    The generated proto field is two bytes when not specified, or when specified
++    as an integer or a string:
++      PPP()
++      PPP(proto=0x21)
++      PPP(proto="Internet Protocol version 4")
++    To explicitly forge a one byte proto field, use the bytes representation:
++      PPP(proto=b'\x21')
+     """
+     def getfield(self, pkt, s):
+         if ord(s[:1]) & 0x01:
+@@ -304,12 +312,18 @@ class _PPPProtoField(EnumField):
+         return super(_PPPProtoField, self).getfield(pkt, s)
+ 
+     def addfield(self, pkt, s, val):
+-        if val < 0x100:
+-            self.fmt = "!B"
+-            self.sz = 1
++        if isinstance(val, bytes):
++            if len(val) == 1:
++                fmt, sz = "!B", 1
++            elif len(val) == 2:
++                fmt, sz = "!H", 2
++            else:
++                raise TypeError('Invalid length for PPP proto')
++            val = struct.Struct(fmt).unpack(val)[0]
+         else:
+-            self.fmt = "!H"
+-            self.sz = 2
++            fmt, sz = "!H", 2
++        self.fmt = fmt
++        self.sz = sz
+         self.struct = struct.Struct(self.fmt)
+         return super(_PPPProtoField, self).addfield(pkt, s, val)