diff --git a/pkg/connection/connectionset.go b/pkg/connection/connectionset.go
index d81c2cd..891e44e 100644
--- a/pkg/connection/connectionset.go
+++ b/pkg/connection/connectionset.go
@@ -22,9 +22,9 @@ const (
 	UDPCode           = 1
 	ICMPCode          = 2
 	MinICMPType int64 = 0
-	MaxICMPType int64 = netp.InformationReply
+	MaxICMPType int64 = 254
 	MinICMPCode int64 = 0
-	MaxICMPCode int64 = 5
+	MaxICMPCode int64 = 255
 	minProtocol int64 = 0
 	maxProtocol int64 = 2
 	MinPort           = 1
diff --git a/pkg/connection/connectionset_test.go b/pkg/connection/connectionset_test.go
index fcdc36d..0e0f435 100644
--- a/pkg/connection/connectionset_test.go
+++ b/pkg/connection/connectionset_test.go
@@ -6,6 +6,7 @@ SPDX-License-Identifier: Apache-2.0
 package connection_test
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -32,6 +33,18 @@ func TestBasicSetICMP(t *testing.T) {
 	require.Equal(t, "ICMP type: 3 code: 5", c.ShortString())
 }
 
+func TestICMPUnion(t *testing.T) {
+	c1 := connection.ICMPConnection(135, 136, connection.MinICMPCode, connection.MaxICMPCode)
+	c2 := connection.ICMPConnection(connection.MinICMPType, connection.MaxICMPType, connection.MinICMPCode, connection.MaxICMPCode)
+	union := c1.Union(c2)
+	fmt.Println(c1.String())
+	fmt.Println(c2.String())
+	fmt.Println(union.String())
+	require.Equal(t, "protocol: ICMP icmp-type: 135-136", c1.String())
+	require.Equal(t, "protocol: ICMP", c2.String())
+	require.Equal(t, "protocol: ICMP", union.String())
+}
+
 func TestBasicSetTCP(t *testing.T) {
 	e := connection.TCPorUDPConnection(netp.ProtocolStringTCP, 1, 65535, 1, 655)
 	require.Equal(t, "protocol: TCP dst-ports: 1-655", e.String())
@@ -58,14 +71,15 @@ func TestBasicSet2(t *testing.T) {
 	except2 := connection.TCPorUDPConnection(netp.ProtocolStringTCP, 1, 65535, 1, 65535)
 
 	d := connection.All().Subtract(except1).Subtract(except2)
+	fmt.Println(d.String())
+	fmt.Println(d.ShortString())
 	require.Equal(t, ""+
-		"protocol: ICMP icmp-type: 0-2,4-16; "+
-		"protocol: ICMP icmp-type: 3 icmp-code: 0-4; "+
-		"protocol: UDP", d.String())
+		"protocol: ICMP icmp-type: 0-2,4-254; "+
+		"protocol: ICMP icmp-type: 3 icmp-code: 0-4,6-255; protocol: UDP",
+		d.String())
 	require.Equal(t, ""+
-		"ICMP type: 0-2,4-16; "+
-		"ICMP type: 3 code: 0-4; "+
-		"UDP", d.ShortString())
+		"ICMP type: 0-2,4-254; ICMP type: 3 code: 0-4,6-255; UDP",
+		d.ShortString())
 }
 
 func TestBasicSet3(t *testing.T) {