diff --git a/rpcserver.go b/rpcserver.go
index 45bcf9b..008b2dc 100644
--- a/rpcserver.go
+++ b/rpcserver.go
@@ -172,41 +172,6 @@ func (c *websocketClient) send(b []byte) error {
 	}
 }
 
-// isManagerLockedError returns whether or not the passed error is due to the
-// address manager being locked.
-func isManagerLockedError(err error) bool {
-	merr, ok := err.(waddrmgr.ManagerError)
-	return ok && merr.ErrorCode == waddrmgr.ErrLocked
-}
-
-// isManagerWrongPassphraseError returns whether or not the passed error is due
-// to the address manager being provided with an invalid passprhase.
-func isManagerWrongPassphraseError(err error) bool {
-	merr, ok := err.(waddrmgr.ManagerError)
-	return ok && merr.ErrorCode == waddrmgr.ErrWrongPassphrase
-}
-
-// isManagerDuplicateAddressError returns whether or not the passed error is due to a
-// duplicate item being provided to the address manager.
-func isManagerDuplicateAddressError(err error) bool {
-	merr, ok := err.(waddrmgr.ManagerError)
-	return ok && merr.ErrorCode == waddrmgr.ErrDuplicateAddress
-}
-
-// isManagerAddressNotFoundError returns whether or not the passed error is due to a
-// the address not being found.
-func isManagerAddressNotFoundError(err error) bool {
-	merr, ok := err.(waddrmgr.ManagerError)
-	return ok && merr.ErrorCode == waddrmgr.ErrAddressNotFound
-}
-
-// isManagerAccountNotFoundError returns whether or not the passed error is due
-// to the account not being found.
-func isManagerAccountNotFoundError(err error) bool {
-	merr, ok := err.(waddrmgr.ManagerError)
-	return ok && merr.ErrorCode == waddrmgr.ErrAccountNotFound
-}
-
 // parseListeners splits the list of listen addresses passed in addrs into
 // IPv4 and IPv6 slices and returns them.  This allows easy creation of the
 // listeners on the correct interface "tcp4" and "tcp6".  It also properly
@@ -1592,7 +1557,7 @@ func DumpPrivKey(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{}) (in
 	}
 
 	key, err := w.DumpWIFPrivateKey(addr)
-	if isManagerLockedError(err) {
+	if waddrmgr.IsError(err, waddrmgr.ErrLocked) {
 		// Address was found, but the private key isn't
 		// accessible.
 		return nil, &ErrWalletUnlockNeeded
@@ -1605,7 +1570,7 @@ func DumpPrivKey(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{}) (in
 // TODO: finish this to match bitcoind by writing the dump to a file.
 func DumpWallet(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{}) (interface{}, error) {
 	keys, err := w.DumpPrivKeys()
-	if isManagerLockedError(err) {
+	if waddrmgr.IsError(err, waddrmgr.ErrLocked) {
 		return nil, &ErrWalletUnlockNeeded
 	}
 
@@ -1848,10 +1813,10 @@ func ImportPrivKey(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{}) (
 	// Import the private key, handling any errors.
 	_, err = w.ImportPrivateKey(wif, nil, *cmd.Rescan)
 	switch {
-	case isManagerDuplicateAddressError(err):
+	case waddrmgr.IsError(err, waddrmgr.ErrDuplicateAddress):
 		// Do not return duplicate key errors to the client.
 		return nil, nil
-	case isManagerLockedError(err):
+	case waddrmgr.IsError(err, waddrmgr.ErrLocked):
 		return nil, &ErrWalletUnlockNeeded
 	}
 
@@ -1893,7 +1858,7 @@ func CreateNewAccount(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{}
 	}
 
 	_, err = w.Manager.NewAccount(cmd.Account)
-	if isManagerLockedError(err) {
+	if waddrmgr.IsError(err, waddrmgr.ErrLocked) {
 		return nil, &btcjson.RPCError{
 			Code: btcjson.ErrRPCWalletUnlockNeeded,
 			Message: "Creating an account requires the wallet to be unlocked. " +
@@ -2599,7 +2564,7 @@ func sendPairs(w *wallet.Wallet, amounts map[string]btcutil.Amount,
 		if err == wallet.ErrNonPositiveAmount {
 			return "", ErrNeedPositiveAmount
 		}
-		if isManagerLockedError(err) {
+		if waddrmgr.IsError(err, waddrmgr.ErrLocked) {
 			return "", &ErrWalletUnlockNeeded
 		}
 		switch err.(type) {
@@ -3111,7 +3076,7 @@ func ValidateAddress(w *wallet.Wallet, chainSvr *chain.Client, icmd interface{})
 
 	ainfo, err := w.Manager.Address(addr)
 	if err != nil {
-		if isManagerAddressNotFoundError(err) {
+		if waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
 			// No additional information available about the address.
 			return result, nil
 		}
@@ -3251,7 +3216,7 @@ func WalletPassphraseChange(w *wallet.Wallet, chainSvr *chain.Client, icmd inter
 
 	err := w.ChangePassphrase([]byte(cmd.OldPassphrase),
 		[]byte(cmd.NewPassphrase))
-	if isManagerWrongPassphraseError(err) {
+	if waddrmgr.IsError(err, waddrmgr.ErrWrongPassphrase) {
 		return nil, &btcjson.RPCError{
 			Code:    btcjson.ErrRPCWalletPassphraseIncorrect,
 			Message: "Incorrect passphrase",
diff --git a/wallet/chainntfns.go b/wallet/chainntfns.go
index d8fe0c8..6ac484f 100644
--- a/wallet/chainntfns.go
+++ b/wallet/chainntfns.go
@@ -191,8 +191,7 @@ func (w *Wallet) addRelevantTx(rec *wtxmgr.TxRecord, block *wtxmgr.BlockMeta) er
 
 			// Missing addresses are skipped.  Other errors should
 			// be propagated.
-			code := err.(waddrmgr.ManagerError).ErrorCode
-			if code != waddrmgr.ErrAddressNotFound {
+			if !waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
 				return err
 			}
 		}
diff --git a/wallet/wallet.go b/wallet/wallet.go
index 93fe1fa..a48567e 100644
--- a/wallet/wallet.go
+++ b/wallet/wallet.go
@@ -752,8 +752,7 @@ func (w *Wallet) CurrentAddress(account uint32) (btcutil.Address, error) {
 	addr, err := w.Manager.LastExternalAddress(account)
 	if err != nil {
 		// If no address exists yet, create the first external address
-		merr, ok := err.(waddrmgr.ManagerError)
-		if ok && merr.ErrorCode == waddrmgr.ErrAddressNotFound {
+		if waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
 			return w.NewAddress(account)
 		}
 		return nil, err
@@ -1349,8 +1348,7 @@ func (w *Wallet) ExportWatchingWallet(pubPass string) (string, error) {
 		// Only return the error is it's not because it's already
 		// watching-only.  When it is already watching-only, the code
 		// just falls through to the export below.
-		if merr, ok := err.(waddrmgr.ManagerError); ok &&
-			merr.ErrorCode != waddrmgr.ErrWatchingOnly {
+		if !waddrmgr.IsError(err, waddrmgr.ErrWatchingOnly) {
 			return "", err
 		}
 	}