diff --git a/.circleci/config.yml b/.circleci/config.yml
index 269085f..2029eda 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -4,7 +4,7 @@ jobs:
   build:
     working_directory: /go/src/github.com/qri-io/starlib
     docker:
-      - image: circleci/golang:1.12
+      - image: circleci/golang:latest
     environment:
       TEST_RESULTS: /tmp/test-results
       GO111MODULE: "on"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9474f9d..0ea22fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,67 @@
+<a name="v0.4.2">v0.4.2</a>
+# [v0.4.2](https://github.com/qri-io/starlib/compare/v0.4.1...v0.4.2) (2020-06-29)
+
+This release brings a number of enhancements to the `time`, `re`, and golang-side utility packages. It also introduces two new packages: `encoding/yaml` and `hash`. Here's the docs for the two new packages:
+
+### yaml
+yaml provides functions for working with yaml data
+
+#### Functions
+
+##### `dumps(obj) string`
+serialize obj to a yaml string
+
+**parameters:**
+
+| name | type | description |
+|------|------|-------------|
+| `obj` | `object` | input object |
+
+
+##### `loads(source) object`
+read a source yaml string to a starlark object
+
+**parameters:**
+
+| name | type | description |
+|------|------|-------------|
+| `source` | `string` | input string of yaml data |
+
+
+### hash
+hash defines hash primitives for starlark.
+
+#### Functions
+
+##### `md5(string) string`
+returns an md5 hash for a string
+
+##### `sha1(string) string`
+returns an sha1 hash for a string
+
+##### `sha256(string) string`
+returns an sha256 hash for a string
+
+
+### Bug Fixes
+
+* **time:** unix() and unix_nano() returns 0 for epoch ([c50ebc2](https://github.com/qri-io/starlib/commit/c50ebc2))
+
+
+### Features
+
+* **customType:** Added support for custom type and fixed bugs ([#49](https://github.com/qri-io/starlib/issues/49)) ([c32c667](https://github.com/qri-io/starlib/commit/c32c667)), closes [#48](https://github.com/qri-io/starlib/issues/48)
+* **encoding/yaml:** encoding yaml package based on gopkg.in/yaml.v2 ([68e22bc](https://github.com/qri-io/starlib/commit/68e22bc))
+* **hash:** add hash module ([686ae7b](https://github.com/qri-io/starlib/commit/686ae7b))
+* **re:** add compile function to regex package ([6fe15cd](https://github.com/qri-io/starlib/commit/6fe15cd))
+* **starlib:** util.Marshal extended compatibility and tests ([a310f83](https://github.com/qri-io/starlib/commit/a310f83))
+* **time:** Add fromtimestamp method ([4e7be49](https://github.com/qri-io/starlib/commit/4e7be49))
+* **time:** Add in_location and format methods ([316e7aa](https://github.com/qri-io/starlib/commit/316e7aa))
+* **time:** Add methods hours(), minutes(), etc to duration ([f374e23](https://github.com/qri-io/starlib/commit/f374e23))
+* **time:** Add unix and unix_nano methods ([7c32cb7](https://github.com/qri-io/starlib/commit/7c32cb7))
+
+
+
 <a name="v0.4.1"></a>
 # [v0.4.1](https://github.com/qri-io/starlib/compare/v0.4.0...v0.4.1) (2019-06-10)
 
diff --git a/util/util_test.go b/util/util_test.go
index 76b8a06..8b99c06 100644
--- a/util/util_test.go
+++ b/util/util_test.go
@@ -153,13 +153,19 @@ type invalidCustomType struct {
 
 type customType invalidCustomType
 
-func (t *customType) UnmarshalStarlark(v starlark.Value) error {
+var (
+	_ Unmarshaler    = (*customType)(nil)
+	_ Marshaler      = (*customType)(nil)
+	_ starlark.Value = (*customType)(nil)
+)
+
+func (c *customType) UnmarshalStarlark(v starlark.Value) error {
 	// asserts
 	if v.Type() != "struct" {
 		return fmt.Errorf("not expected top level type, want struct, got %q", v.Type())
 	}
 	if _, ok := v.(*starlarkstruct.Struct).Constructor().(*customType); !ok {
-		return fmt.Errorf("not expected construct type got %T, want %T", v.(*starlarkstruct.Struct).Constructor(), t)
+		return fmt.Errorf("not expected construct type got %T, want %T", v.(*starlarkstruct.Struct).Constructor(), c)
 	}
 
 	// TODO: refactoring transform data
@@ -172,15 +178,15 @@ func (t *customType) UnmarshalStarlark(v starlark.Value) error {
 	data := starlark.StringDict{}
 	v.(*starlarkstruct.Struct).ToStringDict(data)
 
-	*t = customType{
+	*c = customType{
 		Foo: mustInt64(data["foo"]),
 	}
 	return nil
 }
 
-func (t *customType) MarshalStarlark() (starlark.Value, error) {
+func (c *customType) MarshalStarlark() (starlark.Value, error) {
 	v := starlarkstruct.FromStringDict(&customType{}, starlark.StringDict{
-		"foo": starlark.MakeInt64(t.Foo),
+		"foo": starlark.MakeInt64(c.Foo),
 	})
 	return v, nil
 }
@@ -200,7 +206,3 @@ func (c customType) Truth() starlark.Bool {
 func (c customType) Hash() (uint32, error) {
 	return 0, fmt.Errorf("unhashable: %s", c.Type())
 }
-
-var _ Unmarshaler = (*customType)(nil)
-var _ Marshaler = (*customType)(nil)
-var _ starlark.Value = (*customType)(nil)