diff --git a/signer/signer_trust.go b/signer/signer_trust.go
index e62cacc25b..53ae075415 100644
--- a/signer/signer_trust.go
+++ b/signer/signer_trust.go
@@ -133,6 +133,8 @@ func (trust *NotarySigner) CheckHealth(timeout time.Duration) error {
 	return err
 }
 
+// ImportRootKey satisfies the CryptoService interface. It should not be implemented
+// for a NotarySigner.
 func (trust *NotarySigner) ImportRootKey(r io.Reader) error {
 	return errors.New("Importing a root key to NotarySigner is not supported")
 }
diff --git a/tuf/signed/ed25519.go b/tuf/signed/ed25519.go
index 3ab1e8af78..dc5ea00f23 100644
--- a/tuf/signed/ed25519.go
+++ b/tuf/signed/ed25519.go
@@ -119,6 +119,7 @@ func (e *Ed25519) GetPrivateKey(keyID string) (data.PrivateKey, string, error) {
 	return e.keys[keyID].privKey, "", nil
 }
 
+// ImportRootKey adds an Ed25519 key to the store as a root key
 func (e *Ed25519) ImportRootKey(r io.Reader) error {
 	raw, err := ioutil.ReadAll(r)
 	if err != nil {