diff --git a/types/logroot.go b/types/logroot.go
index 2648a36166..7ef3988e05 100644
--- a/types/logroot.go
+++ b/types/logroot.go
@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package types defines serialization and parsing functions for SignedLogRoot
+// and SignedMapRoot fields.
 package types
 
 import (
@@ -23,7 +25,15 @@ import (
 	"github.com/google/trillian"
 )
 
-// LogRootV1 contains the fields used by clients to verify Trillian Log behavior.
+// LogRootV1 holds the TLS-deserializtion of the following structure
+// (described in RFC5246 section 4 notation):
+// struct {
+//   uint64 tree_size;
+//   opaque root_hash<0..128>;
+//   uint64 timestamp_nanos;
+//   uint64 revision;
+//   opaque metadata<0..65535>;
+// } LogRootV1;
 type LogRootV1 struct {
 	TreeSize       uint64
 	RootHash       []byte `tls:"minlen:0,maxlen:128"`
@@ -32,26 +42,34 @@ type LogRootV1 struct {
 	Metadata       []byte `tls:"minlen:0,maxlen:65535"`
 }
 
-// LogRoot contains the fields serialized into SignedLogRoot.LogRoot
+// LogRoot holds the TLS-deserializtion of the following structure
+// (described in RFC5246 section 4 notation):
+// enum { v1(1), (65535)} Version;
+// struct {
+//   Version version;
+//   select(version) {
+//     case v1: LogRootV1;
+//   }
+// } LogRoot;
 type LogRoot struct {
 	Version tls.Enum   `tls:"size:2"`
 	V1      *LogRootV1 `tls:"selector:Version,val:1"`
 }
 
-// ParseLogRoot verifies that b has the LOG_ROOT_FORMAT_V1 tag and returns a *LogRootV1
-func ParseLogRoot(b []byte) (*LogRootV1, error) {
-	if b == nil {
+// ParseLogRoot verifies that logRootBytes is a TLS serialized LogRoot,
+// has the LOG_ROOT_FORMAT_V1 tag, and returns the deserialized *LogRootV1.
+func ParseLogRoot(logRootBytes []byte) (*LogRootV1, error) {
+	if logRootBytes == nil {
 		return nil, fmt.Errorf("nil log root")
 	}
-	// Verify version
-	version := binary.BigEndian.Uint16(b)
+	version := binary.BigEndian.Uint16(logRootBytes)
 	if version != uint16(trillian.LogRootFormat_LOG_ROOT_FORMAT_V1) {
 		return nil, fmt.Errorf("invalid LogRoot.Version: %v, want %v",
 			version, trillian.LogRootFormat_LOG_ROOT_FORMAT_V1)
 	}
 
 	var logRoot LogRoot
-	if _, err := tls.Unmarshal(b, &logRoot); err != nil {
+	if _, err := tls.Unmarshal(logRootBytes, &logRoot); err != nil {
 		return nil, err
 	}
 	return logRoot.V1, nil
diff --git a/types/logroot_test.go b/types/logroot_test.go
index c3a4567d07..0f7f425d85 100644
--- a/types/logroot_test.go
+++ b/types/logroot_test.go
@@ -60,13 +60,12 @@ func TestParseLogRoot(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			logRoot: []byte("foo"),
-			wantErr: true,
-		},
-		{
-			logRoot: nil,
+			// Correct type, but junk afterwards.
+			logRoot: []byte{0, 1, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5},
 			wantErr: true,
 		},
+		{logRoot: []byte("foo"), wantErr: true},
+		{logRoot: nil, wantErr: true},
 	} {
 		_, err := ParseLogRoot(tc.logRoot)
 		if got, want := err != nil, tc.wantErr; got != want {
diff --git a/types/maproot.go b/types/maproot.go
index 65d976f531..048d4ade10 100644
--- a/types/maproot.go
+++ b/types/maproot.go
@@ -22,7 +22,14 @@ import (
 	"github.com/google/trillian"
 )
 
-// MapRootV1 contains the fields verified by SignedMapRoot
+// MapRootV1 holds the TLS-deserializtion of the following structure
+// (described in RFC5246 section 4 notation):
+// struct {
+//   opaque root_hash<0..128>;
+//   uint64 timestamp_nanos;
+//   uint64 revision;
+//   opaque metadata<0..65535>;
+// } MapRootV1;
 type MapRootV1 struct {
 	RootHash       []byte `tls:"minlen:0,maxlen:128"`
 	TimestampNanos uint64
@@ -30,29 +37,37 @@ type MapRootV1 struct {
 	Metadata       []byte `tls:"minlen:0,maxlen:65535"`
 }
 
-// MapRoot contains the fields serialized into SignedMapRoot.MapRoot
+// MapRoot holds the TLS-deserializtion of the following structure
+// (described in RFC5246 section 4 notation):
+// enum { v1(1), (65535)} Version;
+// struct {
+//   Version version;
+//   select(version) {
+//     case v1: MapRootV1;
+//   }
+// } MapRoot;
 type MapRoot struct {
 	Version tls.Enum   `tls:"size:2"`
 	V1      *MapRootV1 `tls:"selector:Version,val:1"`
 }
 
-// ParseMapRoot verifies that b has the MAP_ROOT_FORMAT_V1 tag and returns a *MapRootV1
-func ParseMapRoot(b []byte) (*MapRootV1, error) {
-	if b == nil {
+// ParseMapRoot verifies that mapRootBytes is a TLS serialized MapRoot,
+// has the MAP_ROOT_FORMAT_V1 tag, and returns the deserialized *MapRootV1.
+func ParseMapRoot(mapRootBytes []byte) (*MapRootV1, error) {
+	if mapRootBytes == nil {
 		return nil, fmt.Errorf("nil map root")
 	}
-	// Verify version
-	version := binary.BigEndian.Uint16(b)
+	version := binary.BigEndian.Uint16(mapRootBytes)
 	if version != uint16(trillian.MapRootFormat_MAP_ROOT_FORMAT_V1) {
 		return nil, fmt.Errorf("invalid MapRoot.Version: %v, want %v",
 			version, trillian.MapRootFormat_MAP_ROOT_FORMAT_V1)
 	}
 
-	var logRoot MapRoot
-	if _, err := tls.Unmarshal(b, &logRoot); err != nil {
+	var mapRoot MapRoot
+	if _, err := tls.Unmarshal(mapRootBytes, &mapRoot); err != nil {
 		return nil, err
 	}
-	return logRoot.V1, nil
+	return mapRoot.V1, nil
 }
 
 // SerializeMapRoot returns a canonical TLS serialization of the map root.
diff --git a/types/maproot_test.go b/types/maproot_test.go
index 6fe4b67d23..6e69b43477 100644
--- a/types/maproot_test.go
+++ b/types/maproot_test.go
@@ -68,6 +68,11 @@ func TestParseMapRoot(t *testing.T) {
 				Metadata: []byte{},
 			}),
 		},
+		{
+			// Correct type, but junk afterwards.
+			mapRoot: []byte{0, 1, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5},
+			wantErr: true,
+		},
 		{mapRoot: []byte("foo"), wantErr: true},
 		{mapRoot: nil, wantErr: true},
 	} {