diff --git a/authority/provisioner/claims.go b/authority/provisioner/claims.go
index c1ba9c5f..2fc68397 100644
--- a/authority/provisioner/claims.go
+++ b/authority/provisioner/claims.go
@@ -1,7 +1,6 @@
 package provisioner
 
 import (
-	"encoding/json"
 	"time"
 
 	"github.com/pkg/errors"
@@ -90,40 +89,3 @@ func (pc *Claims) Validate() error {
 		return nil
 	}
 }
-
-// Duration is a wrapper around Time.Duration to aid with marshal/unmarshal.
-type Duration struct {
-	time.Duration
-}
-
-// MarshalJSON parses a duration string and sets it to the duration.
-//
-// A duration string is a possibly signed sequence of decimal numbers, each with
-// optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
-// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
-func (d *Duration) MarshalJSON() ([]byte, error) {
-	return json.Marshal(d.Duration.String())
-}
-
-// UnmarshalJSON parses a duration string and sets it to the duration.
-//
-// A duration string is a possibly signed sequence of decimal numbers, each with
-// optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
-// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
-func (d *Duration) UnmarshalJSON(data []byte) (err error) {
-	var (
-		s  string
-		_d time.Duration
-	)
-	if d == nil {
-		return errors.New("duration cannot be nil")
-	}
-	if err = json.Unmarshal(data, &s); err != nil {
-		return errors.Wrapf(err, "error unmarshaling %s", data)
-	}
-	if _d, err = time.ParseDuration(s); err != nil {
-		return errors.Wrapf(err, "error parsing %s as duration", s)
-	}
-	d.Duration = _d
-	return
-}
diff --git a/authority/types.go b/authority/types.go
index f0a781d5..0d0f2a90 100644
--- a/authority/types.go
+++ b/authority/types.go
@@ -2,48 +2,10 @@ package authority
 
 import (
 	"encoding/json"
-	"time"
 
 	"github.com/pkg/errors"
 )
 
-// Duration is a wrapper around Time.Duration to aid with marshal/unmarshal.
-type Duration struct {
-	time.Duration
-}
-
-// MarshalJSON parses a duration string and sets it to the duration.
-//
-// A duration string is a possibly signed sequence of decimal numbers, each with
-// optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
-// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
-func (d *Duration) MarshalJSON() ([]byte, error) {
-	return json.Marshal(d.Duration.String())
-}
-
-// UnmarshalJSON parses a duration string and sets it to the duration.
-//
-// A duration string is a possibly signed sequence of decimal numbers, each with
-// optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
-// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
-func (d *Duration) UnmarshalJSON(data []byte) (err error) {
-	var (
-		s  string
-		_d time.Duration
-	)
-	if d == nil {
-		return errors.New("duration cannot be nil")
-	}
-	if err = json.Unmarshal(data, &s); err != nil {
-		return errors.Wrapf(err, "error unmarshalling %s", data)
-	}
-	if _d, err = time.ParseDuration(s); err != nil {
-		return errors.Wrapf(err, "error parsing %s as duration", s)
-	}
-	d.Duration = _d
-	return
-}
-
 // multiString represents a type that can be encoded/decoded in JSON as a single
 // string or an array of strings.
 type multiString []string
diff --git a/authority/types_test.go b/authority/types_test.go
index c49c368f..352c253f 100644
--- a/authority/types_test.go
+++ b/authority/types_test.go
@@ -3,7 +3,6 @@ package authority
 import (
 	"reflect"
 	"testing"
-	"time"
 )
 
 func Test_multiString_First(t *testing.T) {
@@ -101,57 +100,3 @@ func Test_multiString_UnmarshalJSON(t *testing.T) {
 		})
 	}
 }
-
-func TestDuration_UnmarshalJSON(t *testing.T) {
-	type args struct {
-		data []byte
-	}
-	tests := []struct {
-		name    string
-		d       *Duration
-		args    args
-		want    *Duration
-		wantErr bool
-	}{
-		{"empty", new(Duration), args{[]byte{}}, new(Duration), true},
-		{"bad type", new(Duration), args{[]byte(`15`)}, new(Duration), true},
-		{"empty string", new(Duration), args{[]byte(`""`)}, new(Duration), true},
-		{"non duration", new(Duration), args{[]byte(`"15"`)}, new(Duration), true},
-		{"duration", new(Duration), args{[]byte(`"15m30s"`)}, &Duration{15*time.Minute + 30*time.Second}, false},
-		{"nil", nil, args{nil}, nil, true},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if err := tt.d.UnmarshalJSON(tt.args.data); (err != nil) != tt.wantErr {
-				t.Errorf("Duration.UnmarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
-				return
-			}
-			if !reflect.DeepEqual(tt.d, tt.want) {
-				t.Errorf("Duration.UnmarshalJSON() = %v, want %v", tt.d, tt.want)
-			}
-		})
-	}
-}
-
-func Test_duration_MarshalJSON(t *testing.T) {
-	tests := []struct {
-		name    string
-		d       *Duration
-		want    []byte
-		wantErr bool
-	}{
-		{"string", &Duration{15*time.Minute + 30*time.Second}, []byte(`"15m30s"`), false},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			got, err := tt.d.MarshalJSON()
-			if (err != nil) != tt.wantErr {
-				t.Errorf("Duration.MarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
-				return
-			}
-			if !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("Duration.MarshalJSON() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}