diff --git a/cmd/yamlchk/main.go b/cmd/yamlchk/main.go
index 713ef22..aeda33f 100644
--- a/cmd/yamlchk/main.go
+++ b/cmd/yamlchk/main.go
@@ -24,12 +24,12 @@ func main() {
 
 	if len(files) == 0 {
 		flag.Usage()
-		log.Fatalln("no YAML files to check")
+		log.Fatal("no YAML files to check")
 	}
 
 	p, err := filepath.Abs(schemaFile)
 	if err != nil {
-		log.Panicln(err)
+		log.Panic(err)
 	}
 
 	refURL := &url.URL{Scheme: "file", Path: p}
@@ -40,23 +40,24 @@ func main() {
 
 		d, err := os.ReadFile(file)
 		if err != nil {
-			log.Panicln(err)
+			log.Panic(err)
 		}
 
 		m := make(map[string]interface{})
 		if err := yaml.Unmarshal(d, &m); err != nil {
-			log.Panicln(err)
+			log.Panic(err)
 		}
 
 		ret, err := validator.Validate(schemaLoader, validator.NewGoLoader(m))
 		if err != nil {
-			log.Panicln(err)
+			log.Panic(err)
 		}
-		if !ret.Valid() {
-			for _, err := range ret.Errors() {
-				log.Printf("%s\n", err)
-			}
-			log.Panicln(fmt.Sprintf("invalid file: %s", file))
+		if ret.Valid() {
+			continue
 		}
+		for _, err := range ret.Errors() {
+			log.Printf("%s\n", err)
+		}
+		log.Panic(fmt.Sprintf("invalid file: %s", file))
 	}
 }
diff --git a/go.mod b/go.mod
index b867385..601ee7e 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,7 @@ module github.com/anqur/yasch
 go 1.20
 
 require (
+	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137
 	github.com/invopop/jsonschema v0.7.0
 	github.com/xeipuuv/gojsonschema v1.2.0
 	gopkg.in/yaml.v3 v3.0.1
diff --git a/go.sum b/go.sum
index 2c1229a..d92962c 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,5 @@
+github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 h1:s6gZFSlWYmbqAuRjVTiNNhvNRfY2Wxp9nhfyel4rklc=
+github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/iancoleman/orderedmap v0.0.0-20190318233801-ac98e3ecb4b0 h1:i462o439ZjprVSFSZLZxcsoAe592sZB1rci2Z8j4wdk=
@@ -8,8 +10,9 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/stretchr/testify v1.3.1-0.20190311161405-34c6fa2dc709 h1:Ko2LQMrRU+Oy/+EDBwX7eZ2jp3C47eDBB8EIhKTun+I=
 github.com/stretchr/testify v1.3.1-0.20190311161405-34c6fa2dc709/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f h1:J9EGpcZtP0E/raorCMxlFGSTBrsSlaDGf3jU/qvAE2c=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=
 github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 h1:EzJWgHovont7NscjpAxXsDA8S8BMYve8Y5+7cuRE7R0=
@@ -18,5 +21,7 @@ github.com/xeipuuv/gojsonschema v1.2.0 h1:LhYJRs+L4fBtjZUfuSZIKGeVu0QRy8e5Xi7D17
 github.com/xeipuuv/gojsonschema v1.2.0/go.mod h1:anYRn/JVcOK2ZgGU+IjEV4nwlhoK5sQluxsYJ78Id3Y=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/pkg/types/type.go b/pkg/types/type.go
new file mode 100644
index 0000000..56f837c
--- /dev/null
+++ b/pkg/types/type.go
@@ -0,0 +1,54 @@
+package types
+
+import (
+	"time"
+
+	"github.com/alecthomas/units"
+	"github.com/invopop/jsonschema"
+)
+
+type Duration struct{ Dur time.Duration }
+
+func (Duration) JSONSchema() *jsonschema.Schema {
+	return &jsonschema.Schema{
+		Type:        "string",
+		Title:       "Duration",
+		Description: "Go-compatible duration",
+	}
+}
+
+func (d Duration) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+	dur, err := time.ParseDuration(s)
+	if err != nil {
+		return err
+	}
+	d.Dur = dur
+	return nil
+}
+
+type Size struct{ Size units.Base2Bytes }
+
+func (Size) JSONSchema() *jsonschema.Schema {
+	return &jsonschema.Schema{
+		Type:        "string",
+		Title:       "Size",
+		Description: "Go-compatible data size",
+	}
+}
+
+func (s Size) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var r string
+	if err := unmarshal(&r); err != nil {
+		return err
+	}
+	size, err := units.ParseBase2Bytes(r)
+	if err != nil {
+		return err
+	}
+	s.Size = size
+	return nil
+}