diff --git a/internal/pkg/pkg.go b/internal/pkg/pkg.go
index 40bad6f..64df5df 100644
--- a/internal/pkg/pkg.go
+++ b/internal/pkg/pkg.go
@@ -24,6 +24,16 @@ type (
 	ID Checksum
 )
 
+// Encode is abbreviation for base64.URLEncoding.EncodeToString(checksum[:]).
+func Encode(checksum Checksum) string {
+	return base64.URLEncoding.EncodeToString(checksum[:])
+}
+
+// encode is abbreviation for base64.URLEncoding.EncodeToString(checksum[:]).
+func encode(checksum *Checksum) string {
+	return base64.URLEncoding.EncodeToString(checksum[:])
+}
+
 // MustDecode decodes a string representation of [Checksum] and panics if there
 // is a decoding error or the resulting data is too short.
 func MustDecode(s string) (checksum Checksum) {
@@ -143,7 +153,7 @@ func (c *Cache) LoadFile(id ID) (
 ) {
 	pathname = c.base.Append(
 		dirIdentifier,
-		base64.URLEncoding.EncodeToString(id[:]),
+		Encode(id),
 	)
 
 	c.mu.RLock()
@@ -160,15 +170,15 @@ type ChecksumMismatchError struct {
 }
 
 func (e *ChecksumMismatchError) Error() string {
-	return "got " + base64.URLEncoding.EncodeToString(e.Got[:]) +
-		" instead of " + base64.URLEncoding.EncodeToString(e.Want[:])
+	return "got " + Encode(e.Got) +
+		" instead of " + Encode(e.Want)
 }
 
 // pathname returns the content-addressed pathname for a [Checksum].
 func (c *Cache) pathname(checksum *Checksum) *check.Absolute {
 	return c.base.Append(
 		dirChecksum,
-		base64.URLEncoding.EncodeToString(checksum[:]),
+		encode(checksum),
 	)
 }
 
@@ -176,7 +186,7 @@ func (c *Cache) pathname(checksum *Checksum) *check.Absolute {
 func (c *Cache) pathnameIdent(id *ID) *check.Absolute {
 	return c.base.Append(
 		dirIdentifier,
-		base64.URLEncoding.EncodeToString(id[:]),
+		encode((*Checksum)(id)),
 	)
 }
 
diff --git a/internal/pkg/pkg_test.go b/internal/pkg/pkg_test.go
index 1151a68..f295ef0 100644
--- a/internal/pkg/pkg_test.go
+++ b/internal/pkg/pkg_test.go
@@ -3,7 +3,6 @@ package pkg_test
 import (
 	"bytes"
 	"crypto/sha512"
-	"encoding/base64"
 	"io/fs"
 	"net/http"
 	"os"
@@ -51,8 +50,8 @@ func TestIdent(t *testing.T) {
 
 			if got := tc.kind.Ident(tc.params, tc.deps...); got != tc.want {
 				t.Errorf("Ident: %s, want %s",
-					base64.URLEncoding.EncodeToString(got[:]),
-					base64.URLEncoding.EncodeToString(tc.want[:]))
+					pkg.Encode(got),
+					pkg.Encode(tc.want))
 			}
 		})
 	}
@@ -132,7 +131,7 @@ func TestCache(t *testing.T) {
 		return (pkg.Checksum)(h.Sum(nil))
 	}()
 
-	testdataChecksumString := base64.URLEncoding.EncodeToString(testdataChecksum[:])
+	testdataChecksumString := pkg.Encode(testdataChecksum)
 
 	testCases := []cacheTestCase{
 		{"file", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
@@ -267,7 +266,7 @@ func TestCache(t *testing.T) {
 			var gotChecksum pkg.Checksum
 			wantPathnameG := base.Append(
 				"identifier",
-				base64.URLEncoding.EncodeToString(wantChecksum[:]),
+				pkg.Encode(wantChecksum),
 			)
 			if pathname, err := c.StoreFile(
 				wantChecksum,