diff --git a/internal/jimm/sshkeys/types.go b/internal/jimm/sshkeys/types.go
index ac95be4e3..7c0244043 100644
--- a/internal/jimm/sshkeys/types.go
+++ b/internal/jimm/sshkeys/types.go
@@ -6,6 +6,9 @@ import (
 	gossh "golang.org/x/crypto/ssh"
 )
 
+// PublicKey holds a public key and key comment.
+// The public key is any key that is supported by
+// the crypto/ssh PublicKey interface.
 type PublicKey struct {
 	gossh.PublicKey
 	Comment string