diff --git a/store/cache_kvstore.go b/store/cache_kvstore.go
index 105f4fc..755ecdb 100644
--- a/store/cache_kvstore.go
+++ b/store/cache_kvstore.go
@@ -3,18 +3,21 @@ package store
 import (
 	"context"
 
+	corestoretypes "cosmossdk.io/core/store"
 	"cosmossdk.io/errors"
 	cachekv "cosmossdk.io/store/cachekv"
-	"cosmossdk.io/store/types"
+	storetypes "cosmossdk.io/store/types"
 	bigcache "github.com/allegro/bigcache/v3"
 )
 
+var _ corestoretypes.KVStore = (*CacheStore)(nil)
+
 type CacheStore struct {
-	store types.CacheKVStore
+	store storetypes.CacheKVStore
 	cache *bigcache.BigCache
 }
 
-func NewCacheStore(store types.KVStore, capacity int) *CacheStore {
+func NewCacheStore(store storetypes.KVStore, capacity int) *CacheStore {
 	// default with no eviction and custom hard max cache capacity
 	cacheCfg := bigcache.DefaultConfig(0)
 	cacheCfg.Verbose = false
@@ -31,33 +34,48 @@ func NewCacheStore(store types.KVStore, capacity int) *CacheStore {
 	}
 }
 
+// Get returns nil iff key doesn't exist. Errors on nil key.
 func (c CacheStore) Get(key []byte) ([]byte, error) {
-	types.AssertValidKey(key)
+	storetypes.AssertValidKey(key)
 
-	v, err := c.cache.Get(string(key))
-	// cache hit
-	if err == nil {
-		return v, nil
+	if value, err := c.cache.Get(string(key)); err == nil {
+		return value, nil
 	}
 
 	// get from store and write to cache
 	value := c.store.Get(key)
-	err = c.cache.Set(string(key), value)
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to set cache")
+	if value == nil {
+		return nil, nil
 	}
 
+	// ignore cache error
+	_ = c.cache.Set(string(key), value)
+
 	return value, nil
 }
 
+// Has checks if a key exists. Errors on nil key.
 func (c CacheStore) Has(key []byte) (bool, error) {
 	_, err := c.cache.Get(string(key))
-	return err == nil, err
+	if err == nil {
+		return true, nil
+	}
+
+	value := c.store.Get(key)
+	if value == nil {
+		return false, nil
+	}
+
+	// ignore cache error
+	_ = c.cache.Set(string(key), value)
+
+	return true, nil
 }
 
+// Set sets the key. Errors on nil key or value.
 func (c CacheStore) Set(key, value []byte) error {
-	types.AssertValidKey(key)
-	types.AssertValidValue(value)
+	storetypes.AssertValidKey(key)
+	storetypes.AssertValidValue(value)
 
 	err := c.cache.Set(string(key), value)
 	if err != nil {
@@ -68,20 +86,35 @@ func (c CacheStore) Set(key, value []byte) error {
 	return nil
 }
 
+// Delete deletes the key. Errors on nil key.
 func (c CacheStore) Delete(key []byte) error {
-	types.AssertValidKey(key)
+	storetypes.AssertValidKey(key)
 
-	_ = c.cache.Delete(string(key))
+	err := c.cache.Delete(string(key))
+	if err != nil && errors.IsOf(err, bigcache.ErrEntryNotFound) {
+		return errors.Wrap(err, "failed to delete cache")
+	}
 	c.store.Delete(key)
 
 	return nil
 }
 
-func (c CacheStore) Iterator(start, end []byte) (types.Iterator, error) {
+// Iterator iterates over a domain of keys in ascending order. End is exclusive.
+// Start must be less than end, or the Iterator is invalid.
+// Iterator must be closed by caller.
+// To iterate over entire domain, use store.Iterator(nil, nil)
+// CONTRACT: No writes may happen within a domain while an iterator exists over it.
+// Exceptionally allowed for cachekv.Store, safe to write in the modules.
+func (c CacheStore) Iterator(start, end []byte) (storetypes.Iterator, error) {
 	return c.store.Iterator(start, end), nil
 }
 
-func (c CacheStore) ReverseIterator(start, end []byte) (types.Iterator, error) {
+// ReverseIterator iterates over a domain of keys in descending order. End is exclusive.
+// Start must be less than end, or the Iterator is invalid.
+// Iterator must be closed by caller.
+// CONTRACT: No writes may happen within a domain while an iterator exists over it.
+// Exceptionally allowed for cachekv.Store, safe to write in the modules.
+func (c CacheStore) ReverseIterator(start, end []byte) (storetypes.Iterator, error) {
 	return c.store.ReverseIterator(start, end), nil
 }