diff --git a/protocol/minmax.go b/protocol/minmax.go
new file mode 100644
index 000000000..46c262921
--- /dev/null
+++ b/protocol/minmax.go
@@ -0,0 +1,17 @@
+package protocol
+
+// MaxPacketNumber returns the max packet number
+func MaxPacketNumber(a, b PacketNumber) PacketNumber {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+// MinPacketNumber returns the min packet number
+func MinPacketNumber(a, b PacketNumber) PacketNumber {
+	if a < b {
+		return a
+	}
+	return b
+}
diff --git a/protocol/minmax_test.go b/protocol/minmax_test.go
new file mode 100644
index 000000000..1cfbcabaf
--- /dev/null
+++ b/protocol/minmax_test.go
@@ -0,0 +1,17 @@
+package protocol_test
+
+import (
+	"github.com/lucas-clemente/quic-go/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("minmax", func() {
+	It("calculates packet number max", func() {
+		Expect(protocol.MaxPacketNumber(1, 2)).To(Equal(protocol.PacketNumber(2)))
+	})
+
+	It("calculates packet number min", func() {
+		Expect(protocol.MinPacketNumber(1, 2)).To(Equal(protocol.PacketNumber(1)))
+	})
+})