diff --git a/rpc/api/personal.go b/rpc/api/personal.go
index 1b0dea330a..dd2aac2365 100644
--- a/rpc/api/personal.go
+++ b/rpc/api/personal.go
@@ -110,7 +110,7 @@ func (self *personalApi) UnlockAccount(req *shared.Request) (interface{}, error)
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	if len(args.Passphrase) == 0 {
+	if !args.HasPW {
 		fe := self.xeth.Frontend()
 		if fe == nil {
 			return false, fmt.Errorf("No password provided")
diff --git a/rpc/api/personal_args.go b/rpc/api/personal_args.go
index 89419029bd..fac9deebf6 100644
--- a/rpc/api/personal_args.go
+++ b/rpc/api/personal_args.go
@@ -47,6 +47,7 @@ func (args *NewAccountArgs) UnmarshalJSON(b []byte) (err error) {
 type UnlockAccountArgs struct {
 	Address    string
 	Passphrase string
+	HasPW      bool
 	Duration   int
 }
 
@@ -57,6 +58,7 @@ func (args *UnlockAccountArgs) UnmarshalJSON(b []byte) (err error) {
 	}
 
 	args.Duration = 0
+	args.HasPW = false
 
 	if len(obj) < 1 {
 		return shared.NewInsufficientParamsError(len(obj), 1)
@@ -71,6 +73,7 @@ func (args *UnlockAccountArgs) UnmarshalJSON(b []byte) (err error) {
 	if len(obj) >= 2 && obj[1] != nil {
 		if passphrasestr, ok := obj[1].(string); ok {
 			args.Passphrase = passphrasestr
+			args.HasPW = true
 		} else {
 			return shared.NewInvalidTypeError("passphrase", "not a string")
 		}