diff --git a/config/type_port.go b/config/type_port.go
index ea02fbd..892558e 100644
--- a/config/type_port.go
+++ b/config/type_port.go
@@ -14,7 +14,7 @@ func (c *TypePort) UnmarshalJSON(data []byte) error {
 		return nil
 	}
 
-	intValue, err := strconv.ParseUint(string(data), 10, 16)
+	intValue, err := strconv.ParseUint(string(data), 10, 64)
 	if err != nil {
 		return fmt.Errorf("port number is not a number: %w", err)
 	}
diff --git a/config/type_port_test.go b/config/type_port_test.go
index 0bc4bfc..98ab187 100644
--- a/config/type_port_test.go
+++ b/config/type_port_test.go
@@ -18,6 +18,12 @@ type TypePortTestSuite struct {
 	suite.Suite
 }
 
+func (suite *TypePortTestSuite) TestUnmarshalNil() {
+	typ := &config.TypePort{}
+	suite.NoError(typ.UnmarshalJSON(nil))
+	suite.Equal("0", typ.String())
+}
+
 func (suite *TypePortTestSuite) TestUnmarshalFail() {
 	testData := []int{
 		-1,