diff --git a/cmd/kubeadm/app/apis/kubeadm/bootstraptokenhelpers.go b/cmd/kubeadm/app/apis/kubeadm/bootstraptokenhelpers.go
index 3bc0ed5a190..fc18701c616 100644
--- a/cmd/kubeadm/app/apis/kubeadm/bootstraptokenhelpers.go
+++ b/cmd/kubeadm/app/apis/kubeadm/bootstraptokenhelpers.go
@@ -84,24 +84,24 @@ func BootstrapTokenFromSecret(secret *v1.Secret) (*BootstrapToken, error) {
 	// Get the Token ID field from the Secret data
 	tokenID := getSecretString(secret, bootstrapapi.BootstrapTokenIDKey)
 	if len(tokenID) == 0 {
-		return nil, fmt.Errorf("Bootstrap Token Secret has no token-id data: %s\n", secret.Name)
+		return nil, fmt.Errorf("Bootstrap Token Secret has no token-id data: %s", secret.Name)
 	}
 
 	// Enforce the right naming convention
 	if secret.Name != bootstraputil.BootstrapTokenSecretName(tokenID) {
-		return nil, fmt.Errorf("bootstrap token name is not of the form '%s(token-id)'. Actual: %q. Expected: %q\n",
+		return nil, fmt.Errorf("bootstrap token name is not of the form '%s(token-id)'. Actual: %q. Expected: %q",
 			bootstrapapi.BootstrapTokenSecretPrefix, secret.Name, bootstraputil.BootstrapTokenSecretName(tokenID))
 	}
 
 	tokenSecret := getSecretString(secret, bootstrapapi.BootstrapTokenSecretKey)
 	if len(tokenSecret) == 0 {
-		return nil, fmt.Errorf("Bootstrap Token Secret has no token-secret data: %s\n", secret.Name)
+		return nil, fmt.Errorf("Bootstrap Token Secret has no token-secret data: %s", secret.Name)
 	}
 
 	// Create the BootstrapTokenString object based on the ID and Secret
 	bts, err := NewBootstrapTokenStringFromIDAndSecret(tokenID, tokenSecret)
 	if err != nil {
-		return nil, fmt.Errorf("Bootstrap Token Secret is invalid and couldn't be parsed: %v\n", err)
+		return nil, fmt.Errorf("Bootstrap Token Secret is invalid and couldn't be parsed: %v", err)
 	}
 
 	// Get the description (if any) from the Secret
@@ -116,7 +116,7 @@ func BootstrapTokenFromSecret(secret *v1.Secret) (*BootstrapToken, error) {
 		if err != nil {
 			return nil, fmt.Errorf("can't parse expiration time of bootstrap token %q: %v", secret.Name, err)
 		}
-		expires = &metav1.Time{expTime}
+		expires = &metav1.Time{Time: expTime}
 	}
 
 	// Build an usages string slice from the Secret data
diff --git a/cmd/kubeadm/app/apis/kubeadm/bootstraptokenstring.go b/cmd/kubeadm/app/apis/kubeadm/bootstraptokenstring.go
index 8bbd11ebada..440c2534a64 100644
--- a/cmd/kubeadm/app/apis/kubeadm/bootstraptokenstring.go
+++ b/cmd/kubeadm/app/apis/kubeadm/bootstraptokenstring.go
@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// Package kubeadm holds the internal kubeadm API types
 // Note: This file should be kept in sync with the similar one for the external API
 // TODO: The BootstrapTokenString object should move out to either k8s.io/client-go or k8s.io/api in the future
 // (probably as part of Bootstrap Tokens going GA). It should not be staged under the kubeadm API as it is now.
@@ -28,7 +29,7 @@ import (
 )
 
 // BootstrapTokenString is a token of the format abcdef.abcdef0123456789 that is used
-// for both validation of the authenticy of the API server from a joining node's point
+// for both validation of the practically of the API server from a joining node's point
 // of view and as an authentication method for the node in the bootstrap phase of
 // "kubeadm join". This token is and should be short-lived
 type BootstrapTokenString struct {
diff --git a/cmd/kubeadm/app/apis/kubeadm/v1alpha2/bootstraptokenstring.go b/cmd/kubeadm/app/apis/kubeadm/v1alpha2/bootstraptokenstring.go
index 546b8f898b4..d62d5a7438c 100644
--- a/cmd/kubeadm/app/apis/kubeadm/v1alpha2/bootstraptokenstring.go
+++ b/cmd/kubeadm/app/apis/kubeadm/v1alpha2/bootstraptokenstring.go
@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// Package v1alpha2 holds the external kubeadm API types of version v1alpha2
 // Note: This file should be kept in sync with the similar one for the internal API
 // TODO: The BootstrapTokenString object should move out to either k8s.io/client-go or k8s.io/api in the future
 // (probably as part of Bootstrap Tokens going GA). It should not be staged under the kubeadm API as it is now.
@@ -28,7 +29,7 @@ import (
 )
 
 // BootstrapTokenString is a token of the format abcdef.abcdef0123456789 that is used
-// for both validation of the authenticy of the API server from a joining node's point
+// for both validation of the practically of the API server from a joining node's point
 // of view and as an authentication method for the node in the bootstrap phase of
 // "kubeadm join". This token is and should be short-lived
 type BootstrapTokenString struct {
diff --git a/cmd/kubeadm/app/apis/kubeadm/validation/validation.go b/cmd/kubeadm/app/apis/kubeadm/validation/validation.go
index 53afcaeb4c6..ad542f36f00 100644
--- a/cmd/kubeadm/app/apis/kubeadm/validation/validation.go
+++ b/cmd/kubeadm/app/apis/kubeadm/validation/validation.go
@@ -178,6 +178,7 @@ func ValidateDiscoveryFile(discoveryFile string, fldPath *field.Path) field.Erro
 	return allErrs
 }
 
+// ValidateBootstrapTokens validates a slice of BootstrapToken objects
 func ValidateBootstrapTokens(bts []kubeadm.BootstrapToken, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 	for i, bt := range bts {
diff --git a/cmd/kubeadm/app/cmd/options/token.go b/cmd/kubeadm/app/cmd/options/token.go
index 204fdb4342c..2b793f14322 100644
--- a/cmd/kubeadm/app/cmd/options/token.go
+++ b/cmd/kubeadm/app/cmd/options/token.go
@@ -27,6 +27,7 @@ import (
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 )
 
+// NewBootstrapTokenOptions creates a new BootstrapTokenOptions object with the default values
 func NewBootstrapTokenOptions() *BootstrapTokenOptions {
 	bto := &BootstrapTokenOptions{&kubeadmapiv1alpha2.BootstrapToken{}, ""}
 	kubeadmapiv1alpha2.SetDefaults_BootstrapToken(bto.BootstrapToken)
@@ -41,6 +42,7 @@ type BootstrapTokenOptions struct {
 	TokenStr string
 }
 
+// AddTokenFlag adds the --token flag to the given flagset
 func (bto *BootstrapTokenOptions) AddTokenFlag(fs *pflag.FlagSet) {
 	fs.StringVar(
 		&bto.TokenStr, "token", "",
@@ -48,13 +50,15 @@ func (bto *BootstrapTokenOptions) AddTokenFlag(fs *pflag.FlagSet) {
 	)
 }
 
+// AddTTLFlag adds the --token-ttl flag to the given flagset
 func (bto *BootstrapTokenOptions) AddTTLFlag(fs *pflag.FlagSet) {
 	fs.DurationVar(
-		&bto.TTL.Duration, "ttl", bto.TTL.Duration,
+		&bto.TTL.Duration, "token-ttl", bto.TTL.Duration,
 		"The duration before the token is automatically deleted (e.g. 1s, 2m, 3h). If set to '0', the token will never expire",
 	)
 }
 
+// AddUsagesFlag adds the --usages flag to the given flagset
 func (bto *BootstrapTokenOptions) AddUsagesFlag(fs *pflag.FlagSet) {
 	fs.StringSliceVar(
 		&bto.Usages, "usages", bto.Usages,
@@ -62,6 +66,7 @@ func (bto *BootstrapTokenOptions) AddUsagesFlag(fs *pflag.FlagSet) {
 	)
 }
 
+// AddGroupsFlag adds the --groups flag to the given flagset
 func (bto *BootstrapTokenOptions) AddGroupsFlag(fs *pflag.FlagSet) {
 	fs.StringSliceVar(
 		&bto.Groups, "groups", bto.Groups,
@@ -69,6 +74,7 @@ func (bto *BootstrapTokenOptions) AddGroupsFlag(fs *pflag.FlagSet) {
 	)
 }
 
+// AddDescriptionFlag adds the --description flag to the given flagset
 func (bto *BootstrapTokenOptions) AddDescriptionFlag(fs *pflag.FlagSet) {
 	fs.StringVar(
 		&bto.Description, "description", bto.Description,
@@ -76,6 +82,8 @@ func (bto *BootstrapTokenOptions) AddDescriptionFlag(fs *pflag.FlagSet) {
 	)
 }
 
+// ApplyTo applies the values set internally in the BootstrapTokenOptions object to a MasterConfiguration object at runtime
+// If --token was specified in the CLI (as a string), it's parsed and validated before it's added to the BootstrapToken object.
 func (bto *BootstrapTokenOptions) ApplyTo(cfg *kubeadmapiv1alpha2.MasterConfiguration) error {
 	if len(bto.TokenStr) > 0 {
 		var err error
diff --git a/cmd/kubeadm/app/util/config/masterconfig.go b/cmd/kubeadm/app/util/config/masterconfig.go
index 1b5bb95e51d..c74f93109ea 100644
--- a/cmd/kubeadm/app/util/config/masterconfig.go
+++ b/cmd/kubeadm/app/util/config/masterconfig.go
@@ -66,7 +66,7 @@ func SetInitDynamicDefaults(cfg *kubeadmapi.MasterConfiguration) error {
 
 	// Populate the .Token field with a random value if unset
 	// We do this at this layer, and not the API defaulting layer
-	// because of possible security concerns, and more practially
+	// because of possible security concerns, and more practically
 	// because we can't return errors in the API object defaulting
 	// process but here we can.
 	for i, bt := range cfg.BootstrapTokens {