diff --git a/Godeps/_workspace/src/github.com/cloudflare/cfssl/crypto/pkcs11key/pkcs11key.go b/Godeps/_workspace/src/github.com/cloudflare/cfssl/crypto/pkcs11key/pkcs11key.go
index f1cdd8103..a3a3e3c3b 100644
--- a/Godeps/_workspace/src/github.com/cloudflare/cfssl/crypto/pkcs11key/pkcs11key.go
+++ b/Godeps/_workspace/src/github.com/cloudflare/cfssl/crypto/pkcs11key/pkcs11key.go
@@ -8,6 +8,7 @@ import (
 	"crypto"
 	"crypto/rsa"
 	"errors"
+	"fmt"
 	"io"
 	"math/big"
 
@@ -34,9 +35,13 @@ type PKCS11Key struct {
 	// The PKCS#11 library to use
 	module *pkcs11.Ctx
 
-	// The name of the slot to be used.
+	// The slot id of the token to be used. Both this and tokenLabel must match to
+	// be used.
+	slotID int
+
+	// The label of the token to be used.
 	// We will automatically search for this in the slot list.
-	slotDescription string
+	tokenLabel string
 
 	// The PIN to be used to log in to the device
 	pin string
@@ -49,7 +54,7 @@ type PKCS11Key struct {
 }
 
 // New instantiates a new handle to a PKCS #11-backed key.
-func New(module, slot, pin, privLabel string) (ps *PKCS11Key, err error) {
+func New(module, tokenLabel, pin, privLabel string, slotID int) (ps *PKCS11Key, err error) {
 	// Set up a new pkcs11 object and initialize it
 	p := pkcs11.New(module)
 	if p == nil {
@@ -63,9 +68,10 @@ func New(module, slot, pin, privLabel string) (ps *PKCS11Key, err error) {
 
 	// Initialize a partial key
 	ps = &PKCS11Key{
-		module:          p,
-		slotDescription: slot,
-		pin:             pin,
+		module:     p,
+		slotID:     slotID,
+		tokenLabel: tokenLabel,
+		pin:        pin,
 	}
 
 	// Look up the private key
@@ -159,35 +165,38 @@ func (ps *PKCS11Key) Destroy() {
 }
 
 func (ps *PKCS11Key) openSession() (session pkcs11.SessionHandle, err error) {
-	// Find slot by description
-	slots, err := ps.module.GetSlotList(true)
+	// Check if there is a PCKS11 token with slots. It has side-effects that
+	// allow the rest of the code here to work.
+	_, err = ps.module.GetSlotList(true)
 	if err != nil {
 		return
 	}
-	for _, slot := range slots {
-		slotInfo, err := ps.module.GetSlotInfo(slot)
-		if err != nil {
-			continue
-		}
 
-		if slotInfo.SlotDescription == ps.slotDescription {
-			// Open session
-			session, err = ps.module.OpenSession(slot, pkcs11.CKF_SERIAL_SESSION)
-			if err != nil {
-				return session, err
-			}
-
-			// Login
-			if err = ps.module.Login(session, pkcs11.CKU_USER, ps.pin); err != nil {
-				return session, err
-			}
-
-			return session, err
-		}
+	slotID := uint(ps.slotID)
+	// Look up slot by id
+	tokenInfo, err := ps.module.GetTokenInfo(slotID)
+	if err != nil {
+		return
 	}
 
-	err = errors.New("slot not found")
-	return
+	// Check that token label matches.
+	if tokenInfo.Label != ps.tokenLabel {
+		err = fmt.Errorf("Token label in slot %d was '%s', expected '%s'",
+			slotID, tokenInfo.Label, ps.tokenLabel)
+		return
+	}
+	// Open session
+	session, err = ps.module.OpenSession(slotID, pkcs11.CKF_SERIAL_SESSION)
+	if err != nil {
+		return session, err
+	}
+
+	// Login
+	if err = ps.module.Login(session, pkcs11.CKU_USER, ps.pin); err != nil {
+		return session, err
+	}
+
+	return session, err
 }
 
 func (ps *PKCS11Key) closeSession(session pkcs11.SessionHandle) {
diff --git a/ca/certificate-authority.go b/ca/certificate-authority.go
index 339369425..1b55430d4 100644
--- a/ca/certificate-authority.go
+++ b/ca/certificate-authority.go
@@ -157,8 +157,16 @@ func loadKey(keyConfig cmd.KeyConfig) (priv crypto.Signer, err error) {
 	}
 
 	pkcs11Config := keyConfig.PKCS11
+	if pkcs11Config.Module == "" ||
+		pkcs11Config.TokenLabel == "" ||
+		pkcs11Config.PIN == "" ||
+		pkcs11Config.PrivateKeyLabel == "" ||
+		pkcs11Config.SlotID == nil {
+		err = fmt.Errorf("Missing a field in pkcs11Config %#v", pkcs11Config)
+		return
+	}
 	priv, err = pkcs11key.New(pkcs11Config.Module,
-		pkcs11Config.Token, pkcs11Config.PIN, pkcs11Config.Label)
+		pkcs11Config.TokenLabel, pkcs11Config.PIN, pkcs11Config.PrivateKeyLabel, *pkcs11Config.SlotID)
 	return
 }
 
diff --git a/cmd/shell.go b/cmd/shell.go
index 68912b578..5f50d6e09 100644
--- a/cmd/shell.go
+++ b/cmd/shell.go
@@ -226,10 +226,11 @@ type KeyConfig struct {
 
 // PKCS11Config defines how to load a module for an HSM.
 type PKCS11Config struct {
-	Module string
-	Token  string
-	PIN    string
-	Label  string
+	Module          string
+	TokenLabel      string
+	SlotID          *int
+	PIN             string
+	PrivateKeyLabel string
 }
 
 // TLSConfig reprents certificates and a key for authenticated TLS.
diff --git a/cmd/single-ocsp/main.go b/cmd/single-ocsp/main.go
index 2e91db44d..b38b6cf61 100644
--- a/cmd/single-ocsp/main.go
+++ b/cmd/single-ocsp/main.go
@@ -22,10 +22,11 @@ import (
 // PKCS11Config defines how to load a module for an HSM.
 // XXX(rlb@ipv.sx) Copied from certificate-authority.go
 type PKCS11Config struct {
-	Module string
-	Token  string
-	PIN    string
-	Label  string
+	Module          string
+	TokenLabel      string
+	PrivateKeyLabel string
+	PIN             string
+	SlotID          float64
 }
 
 func readFiles(c *cli.Context) (issuer, responder, target *x509.Certificate, template ocsp.Response, pkcs11 PKCS11Config, err error) {
@@ -158,7 +159,7 @@ func main() {
 		cmd.FailOnError(err, "Failed to read files")
 
 		// Instantiate the private key from PKCS11
-		priv, err := pkcs11key.New(pkcs11.Module, pkcs11.Token, pkcs11.PIN, pkcs11.Label)
+		priv, err := pkcs11key.New(pkcs11.Module, pkcs11.TokenLabel, pkcs11.PIN, pkcs11.PrivateKeyLabel, int(pkcs11.SlotID))
 		cmd.FailOnError(err, "Failed to load PKCS#11 key")
 
 		// Populate the remaining fields in the template
diff --git a/cmd/single-ocsp/test/gentest.go b/cmd/single-ocsp/test/gentest.go
index 5e0ef3db2..30b84b65b 100644
--- a/cmd/single-ocsp/test/gentest.go
+++ b/cmd/single-ocsp/test/gentest.go
@@ -52,16 +52,18 @@ func toPEM(cert *x509.Certificate) []byte {
 func main() {
 	// Instantiate the PKCS11 key
 	var pkcs11 struct {
-		Module string
-		Token  string
-		PIN    string
-		Label  string
+		Module          string
+		TokenLabel      string
+		PIN             string
+		PrivateKeyLabel string
+		SlotID          float64
 	}
 	pkcs11Bytes, err := ioutil.ReadFile(pkcs11FileName)
 	panicOnError(err)
 	err = json.Unmarshal(pkcs11Bytes, &pkcs11)
 	panicOnError(err)
-	p11key, err := pkcs11key.New(pkcs11.Module, pkcs11.Token, pkcs11.PIN, pkcs11.Label)
+	slotID := int(pkcs11.SlotID)
+	p11key, err := pkcs11key.New(pkcs11.Module, pkcs11.TokenLabel, pkcs11.PIN, pkcs11.PrivateKeyLabel, slotID)
 	panicOnError(err)
 
 	// All of the certificates start and end at the same time
diff --git a/cmd/single-ocsp/test/pkcs11.json b/cmd/single-ocsp/test/pkcs11.json
index 0903ff9fd..e9c777382 100644
--- a/cmd/single-ocsp/test/pkcs11.json
+++ b/cmd/single-ocsp/test/pkcs11.json
@@ -1,6 +1,7 @@
 {
-  "Module": "/Library/OpenSC/lib/opensc-pkcs11.so",
-  "Token": "Yubico Yubikey NEO CCID",
-  "Label": "PIV AUTH key",
-  "PIN": "123456"
+  "Module": "/usr/local/Cellar/opensc/0.14.0_1/lib/opensc-pkcs11.so",
+  "TokenLabel": "PIV_II (PIV Card Holder pin)",
+  "SlotID": 1,
+  "PrivateKeyLabel": "SIGN key",
+  "PIN": "163246"
 }
diff --git a/ra/registration-authority_test.go b/ra/registration-authority_test.go
index 5cbb69aa7..f3f9cf4a8 100644
--- a/ra/registration-authority_test.go
+++ b/ra/registration-authority_test.go
@@ -258,7 +258,7 @@ func assertAuthzEqual(t *testing.T, a1, a2 core.Authorization) {
 	if a1.Expires == nil && a2.Expires == nil {
 		return
 	} else if a1.Expires == nil || a2.Expires == nil {
-		t.Errorf("one and only one of authorization's Expires was nil; ret %s, DB %s", a1, a2)
+		t.Errorf("one and only one of authorization's Expires was nil; ret %+v, DB %+v", a1, a2)
 	} else {
 		test.Assert(t, a1.Expires.Equal(*a2.Expires), "ret != DB: Expires")
 	}
diff --git a/sa/storage-authority_test.go b/sa/storage-authority_test.go
index 206c73e6b..64198d473 100644
--- a/sa/storage-authority_test.go
+++ b/sa/storage-authority_test.go
@@ -433,7 +433,7 @@ func TestMarkCertificateRevoked(t *testing.T) {
 	test.AssertNotError(t, err, "Failed to fetch certificate status")
 
 	if code != afterStatus.RevokedReason {
-		t.Errorf("RevokedReasons, expected %s, got %s", code, afterStatus.RevokedReason)
+		t.Errorf("RevokedReasons, expected %d, got %d", code, afterStatus.RevokedReason)
 	}
 	if !fc.Now().Equal(afterStatus.RevokedDate) {
 		t.Errorf("RevokedData, expected %s, got %s", fc.Now(), afterStatus.RevokedDate)