diff --git a/core/overlay/state_transition.go b/core/overlay/state_transition.go
index 2976a0fda2..58680cae30 100644
--- a/core/overlay/state_transition.go
+++ b/core/overlay/state_transition.go
@@ -33,8 +33,6 @@ var (
 )
 
 // StorageReader is a minimal interface for reading contract storage slots.
-// It is satisfied by *state.flatReader, allowing the transition state to be
-// loaded without a full state.StateDB.
 type StorageReader interface {
 	Storage(addr common.Address, slot common.Hash) (common.Hash, error)
 }
@@ -94,9 +92,6 @@ func IsTransitionActive(reader StorageReader) bool {
 // transition registry system contract storage. Returns nil when the
 // registry has not been initialised (i.e. the chain has not yet reached the
 // UBT fork block).
-//
-// The root parameter is unused; it is retained on the signature so callers
-// can express the state version they intend to read.
 func LoadTransitionState(reader StorageReader) (*TransitionState, error) {
 	started, err := reader.Storage(params.BinaryTransitionRegistryAddress, transitionStartedKey)
 	if err != nil {
diff --git a/core/state/database_ubt.go b/core/state/database_ubt.go
index e17dd48b67..287d683a8f 100644
--- a/core/state/database_ubt.go
+++ b/core/state/database_ubt.go
@@ -30,13 +30,6 @@ import (
 )
 
 // UBTDatabase is an implementation of Database interface for Unified Binary Trie.
-//
-// In its plain form it uses a single binary trie database. During the
-// MPT-to-binary transition, an optional MPT trie database (mpttriedb) and a
-// frozen base root provide read-only access to pre-transition state. The
-// wrapInTransitionTrie flag controls whether reads at this database are
-// served via a TransitionTrie that overlays the binary trie on the MPT
-// base; it is normally driven by chainConfig.UBTTransitionActive.
 type UBTDatabase struct {
 	triedb               *triedb.Database
 	mpttriedb            *triedb.Database
@@ -49,9 +42,6 @@ type UBTDatabase struct {
 func (db *UBTDatabase) Type() DatabaseType { return TypeUBT }
 
 // NewUBTDatabase creates a state database with the Unified binary trie manner.
-// State access is wrapped in a TransitionTrie by default (which degenerates
-// to a passthrough when there is no MPT base) so callers that don't care
-// about the override get sensible defaults.
 func NewUBTDatabase(triedb *triedb.Database, codedb *CodeDB) *UBTDatabase {
 	if codedb == nil {
 		codedb = NewCodeDB(triedb.Disk())