diff --git a/cmd/bnscli/cmd_key.go b/cmd/bnscli/cmd_key.go
index 30e6d6e1..653d95f0 100644
--- a/cmd/bnscli/cmd_key.go
+++ b/cmd/bnscli/cmd_key.go
@@ -70,7 +70,7 @@ created. This command fails if the private key file already exists.
 // keygen returns a private key generated using given mnemonic and derivation
 // path.
 func keygen(mnemonic, derivationPath string) (ed25519.PrivateKey, error) {
-	if !bip39.IsMnemonicValid(string(mnemonic)) {
+	if !isMnemonicValid(string(mnemonic)) {
 		return nil, errors.New("invalid mnemonic")
 	}
 
@@ -89,6 +89,15 @@ func keygen(mnemonic, derivationPath string) (ed25519.PrivateKey, error) {
 	return priv, nil
 }
 
+// isMnemonicValid returns true if given mnemonic string is valid. Whitespaces
+// are ignored.
+// Use this instead of bip39.IsMnemonicValid because this function ensures the
+// checksum consistency. bip39.IsMnemonicValid does not test the checksum.
+func isMnemonicValid(mnemonic string) bool {
+	_, err := bip39.EntropyFromMnemonic(mnemonic)
+	return err == nil
+}
+
 func cmdKeyaddr(input io.Reader, output io.Writer, args []string) error {
 	fl := flag.NewFlagSet("", flag.ExitOnError)
 	fl.Usage = func() {
@@ -147,6 +156,7 @@ func cmdMnemonic(input io.Reader, output io.Writer, args []string) error {
 		fmt.Fprint(flag.CommandLine.Output(), `
 Generate and print out a mnemonic. Keep the result in safe place!
 `)
+		fl.PrintDefaults()
 	}
 	var (
 		bitSizeFl = fl.Uint("size", 256, "Bit size of the entropy. Must be between 128 and 256.")
diff --git a/cmd/bnscli/cmd_key_test.go b/cmd/bnscli/cmd_key_test.go
index 76bddec0..bd3bc980 100644
--- a/cmd/bnscli/cmd_key_test.go
+++ b/cmd/bnscli/cmd_key_test.go
@@ -45,19 +45,19 @@ func TestMnemonic(t *testing.T) {
 	}{
 
 		"valid mnemonic 12 words": {
-			mnemonic: "usage mountain noodle inspire distance lyrics caution wait mansion never announce biology",
+			mnemonic: "super bulk plunge better rookie donor reward obscure rescue type trade pelican",
 			wantErr:  false,
 		},
 		"valid mnemonic 15 words": {
-			mnemonic: "usage mountain noodle inspire distance lyrics caution wait mansion never announce biology squirrel guess key",
+			mnemonic: "say debris entry orange grief deer train until flock scrub volume artist skill obscure immense",
 			wantErr:  false,
 		},
 		"valid mnemonic 18 words": {
-			mnemonic: "usage mountain noodle inspire distance lyrics caution wait mansion never announce biology squirrel guess key gain belt same",
+			mnemonic: "fetch height snow poverty space follow seven festival wasp pet asset tattoo cement twist exile trend bench eternal",
 			wantErr:  false,
 		},
 		"valid mnemonic 21 words": {
-			mnemonic: "usage mountain noodle inspire distance lyrics caution wait mansion never announce biology squirrel guess key gain belt same matrix chase mom",
+			mnemonic: "increase shine pumpkin curtain trash cabbage juice canal ugly naive name insane indoor assault snap taxi casual unhappy buddy defense artefact",
 			wantErr:  false,
 		},
 		"valid mnemonic 24 words": {
@@ -66,11 +66,13 @@ func TestMnemonic(t *testing.T) {
 		},
 		"additional whitespace around mnemonnic is ignored": {
 			mnemonic: `
-			usage
-				mountain
-			noodle
-			inspire distance lyrics caution wait mansion
-					never announce biology
+			forget
+				rely tiny
+			ostrich drop edit
+			assault mechanic pony extend
+			together twelve
+				  observe bullet dream
+		  short glide crack orchard exotic zero fly spice final
 			`,
 			wantErr: false,
 		},
@@ -82,6 +84,10 @@ func TestMnemonic(t *testing.T) {
 			mnemonic: " あつかう あっしゅく あつまり あつめる あてな あてはまる あひる あぶら あぶる あふれる あまい あまど ",
 			wantErr:  true,
 		},
+		"initially valid mnemonic that the last word was changed": {
+			mnemonic: "super bulk plunge better rookie donor reward obscure rescue type trade trade",
+			wantErr:  true,
+		},
 	}
 
 	for testName, tc := range cases {
diff --git a/go.mod b/go.mod
index bc94e572..96c610b8 100644
--- a/go.mod
+++ b/go.mod
@@ -23,7 +23,7 @@ require (
 	github.com/tendermint/go-amino v0.15.0
 	github.com/tendermint/iavl v0.12.2
 	github.com/tendermint/tendermint v0.31.5
-	github.com/tyler-smith/go-bip39 v1.0.0
+	github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef
 	golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f
 	google.golang.org/grpc v1.21.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 11266ab3..d2979bac 100644
--- a/go.sum
+++ b/go.sum
@@ -125,8 +125,8 @@ github.com/tendermint/iavl v0.12.2 h1:Ls5p5VINCM1HRT9g5Vvs2zmDOCU/CCIvIHzd/pZ8P0
 github.com/tendermint/iavl v0.12.2/go.mod h1:EoKMMv++tDOL5qKKVnoIqtVPshRrEPeJ0WsgDOLAauM=
 github.com/tendermint/tendermint v0.31.5 h1:vTet8tCq3B9/J9Yo11dNZ8pOB7NtSy++bVSfkP4KzR4=
 github.com/tendermint/tendermint v0.31.5/go.mod h1:ymcPyWblXCplCPQjbOYbrF1fWnpslATMVqiGgWbZrlc=
-github.com/tyler-smith/go-bip39 v1.0.0 h1:FOHg9gaQLeBBRbHE/QrTLfEiBHy5pQ/yXzf9JG5pYFM=
-github.com/tyler-smith/go-bip39 v1.0.0/go.mod h1:sJ5fKU0s6JVwZjjcUEX2zFOnvq0ASQ2K9Zr6cf67kNs=
+github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef h1:wHSqTBrZW24CsNJDfeh9Ex6Pm0Rcpc7qrgKBiL44vF4=
+github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef/go.mod h1:sJ5fKU0s6JVwZjjcUEX2zFOnvq0ASQ2K9Zr6cf67kNs=
 golang.org/x/crypto v0.0.0-20170930174604-9419663f5a44/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=