diff --git a/cmd/hsm/main.go b/cmd/hsm/main.go
index 743a8fcd9..657c946a1 100644
--- a/cmd/hsm/main.go
+++ b/cmd/hsm/main.go
@@ -3,10 +3,17 @@ package main
 import (
 	"os"
 
-	tc "github.com/tendermint/tendermint/cmd/tendermint/commands"
 	"github.com/tendermint/tmlibs/cli"
+	"github.com/tendermint/tmlibs/log"
 
-	"github.com/tendermint/tendermint/cmd/hsm/commands"
+	tc "github.com/tendermint/tendermint/cmd/tendermint/commands"
+	cfg "github.com/tendermint/tendermint/config"
+	"github.com/tendermint/tendermint/types"
+)
+
+var (
+	config = cfg.DefaultConfig()
+	logger = log.NewTMLogger(log.NewSyncWriter(os.Stdout)).With("module", "main")
 )
 
 func main() {
@@ -28,7 +35,9 @@ func main() {
 	rootCmd.AddCommand(tc.TestnetFilesCmd)
 	rootCmd.AddCommand(tc.VersionCmd)
 
-	rootCmd.AddCommand(commands.RunNodeCmd)
+	privValidator := types.LoadOrGenPrivValidator(config.PrivValidatorFile(), logger)
+	privValidator.SetSigner(types.NewDefaultSigner(privValidator.PrivKey))
+	rootCmd.AddCommand(tc.NewRunNodeCmd(privValidator))
 
 	cmd := cli.PrepareBaseCmd(rootCmd, "TM", os.ExpandEnv("$HOME/.tendermint"))
 	cmd.Execute()
diff --git a/cmd/tendermint/commands/run_node.go b/cmd/tendermint/commands/run_node.go
index 413e2cc7a..51b370300 100644
--- a/cmd/tendermint/commands/run_node.go
+++ b/cmd/tendermint/commands/run_node.go
@@ -5,16 +5,59 @@ import (
 
 	"github.com/spf13/cobra"
 
+	cmn "github.com/tendermint/tmlibs/common"
+
 	"github.com/tendermint/tendermint/node"
+	"github.com/tendermint/tendermint/proxy"
 	"github.com/tendermint/tendermint/types"
 )
 
+// RunNodeCmd creates and starts a tendermint node.
 var RunNodeCmd = &cobra.Command{
 	Use:   "node",
 	Short: "Run the tendermint node",
 	RunE:  runNode,
 }
 
+// NewRunNodeCmd creates and starts a tendermint node. It allows the user to
+// use a custom PrivValidator.
+func NewRunNodeCmd(privVal *types.PrivValidator) *cobra.Command {
+	return &cobra.Command{
+		Use:   "node",
+		Short: "Run the tendermint node",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			// Wait until the genesis doc becomes available
+			// This is for Mintnet compatibility.
+			// TODO: If Mintnet gets deprecated or genesis_file is
+			// always available, remove.
+			genDocFile := config.GenesisFile()
+			for !cmn.FileExists(genDocFile) {
+				logger.Info(cmn.Fmt("Waiting for genesis file %v...", genDocFile))
+				time.Sleep(time.Second)
+			}
+
+			genDoc, err := types.GenesisDocFromFile(genDocFile)
+			if err != nil {
+				return err
+			}
+			config.ChainID = genDoc.ChainID
+
+			// Create & start node
+			n := node.NewNode(config, privVal, proxy.DefaultClientCreator(config.ProxyApp, config.ABCI, config.DBDir()), logger)
+			if _, err := n.Start(); err != nil {
+				return fmt.Errorf("Failed to start node: %v", err)
+			} else {
+				logger.Info("Started node", "nodeInfo", n.Switch().NodeInfo())
+			}
+
+			// Trap signal, run forever.
+			n.RunForever()
+
+			return nil
+		},
+	}
+}
+
 func init() {
 	AddNodeFlags(RunNodeCmd)
 }
diff --git a/types/priv_validator.go b/types/priv_validator.go
index 3e84e7f36..072b394ca 100644
--- a/types/priv_validator.go
+++ b/types/priv_validator.go
@@ -35,6 +35,7 @@ func voteToStep(vote *Vote) int8 {
 	}
 }
 
+// PrivValidator implements the functionality for signing blocks.
 type PrivValidator struct {
 	Address       data.Bytes       `json:"address"`
 	PubKey        crypto.PubKey    `json:"pub_key"`
@@ -58,26 +59,29 @@ type PrivValidator struct {
 // It is the caller's duty to verify the msg before calling Sign,
 // eg. to avoid double signing.
 // Currently, the only callers are SignVote and SignProposal
+// Signer is an interface that describes how to sign votes.
 type Signer interface {
 	PubKey() crypto.PubKey
 	Sign(msg []byte) (crypto.Signature, error)
 }
 
-// Implements Signer
+// DefaultSigner implements Signer.
 type DefaultSigner struct {
 	priv crypto.PrivKey
 }
 
+// NewDefaultSigner returns an instance of DefaultSigner.
 func NewDefaultSigner(priv crypto.PrivKey) *DefaultSigner {
 	return &DefaultSigner{priv: priv}
 }
 
-// Implements Signer
+// Sign implements Signer. It signs the byte slice with a private key.
 func (ds *DefaultSigner) Sign(msg []byte) (crypto.Signature, error) {
 	return ds.priv.Sign(msg), nil
 }
 
-// Implements Signer
+// PubKey implements Signer. It should return the public key that corresponds
+// to the private key used for signing.
 func (ds *DefaultSigner) PubKey() crypto.PubKey {
 	return ds.priv.PubKey()
 }