diff --git a/rpc/api.go b/rpc/api.go
index 0f5bac657..ff166264b 100644
--- a/rpc/api.go
+++ b/rpc/api.go
@@ -212,7 +212,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		args := new(HashIndexArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 		}
-		tx := api.xeth().EthTransactionByHash(args.Hash)
+		tx := api.xeth().EthTransactionByHash(args.Hash.Hex())
 		if tx != nil {
 			*reply = NewTransactionRes(tx)
 		}
@@ -222,7 +222,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 			return err
 		}
 
-		block := api.xeth().EthBlockByHexstring(args.Hash)
+		block := api.xeth().EthBlockByHash(args.Hash)
 		br := NewBlockRes(block)
 		br.fullTx = true
 
@@ -250,7 +250,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 			return err
 		}
 
-		br := NewBlockRes(api.xeth().EthBlockByHexstring(args.Hash))
+		br := NewBlockRes(api.xeth().EthBlockByHash(args.Hash))
 
 		if args.Index > int64(len(br.Uncles)) || args.Index < 0 {
 			return NewValidationError("Index", "does not exist")
diff --git a/rpc/args.go b/rpc/args.go
index 34ed84fc2..d3449928b 100644
--- a/rpc/args.go
+++ b/rpc/args.go
@@ -342,7 +342,7 @@ func (args *BlockNumIndexArgs) UnmarshalJSON(b []byte) (err error) {
 }
 
 type HashIndexArgs struct {
-	Hash  string
+	Hash  common.Hash
 	Index int64
 }
 
@@ -361,7 +361,7 @@ func (args *HashIndexArgs) UnmarshalJSON(b []byte) (err error) {
 	if !ok {
 		return NewInvalidTypeError("hash", "not a string")
 	}
-	args.Hash = arg0
+	args.Hash = common.HexToHash(arg0)
 
 	if len(obj) > 1 {
 		arg1, ok := obj[1].(string)
diff --git a/rpc/args_test.go b/rpc/args_test.go
index 82bdcd257..ab74721b3 100644
--- a/rpc/args_test.go
+++ b/rpc/args_test.go
@@ -1139,7 +1139,7 @@ func TestBlockNumIndexArgsIndexInvalid(t *testing.T) {
 func TestHashIndexArgs(t *testing.T) {
 	input := `["0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b", "0x1"]`
 	expected := new(HashIndexArgs)
-	expected.Hash = "0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b"
+	expected.Hash = common.HexToHash("0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b")
 	expected.Index = 1
 
 	args := new(HashIndexArgs)
@@ -1156,6 +1156,66 @@ func TestHashIndexArgs(t *testing.T) {
 	}
 }
 
+func TestHashIndexArgsEmpty(t *testing.T) {
+	input := `[]`
+
+	args := new(HashIndexArgs)
+	err := json.Unmarshal([]byte(input), &args)
+	switch err.(type) {
+	case nil:
+		t.Error("Expected error but didn't get one")
+	case *InsufficientParamsError:
+		break
+	default:
+		t.Errorf("Expected *rpc.InsufficientParamsError but got %T with message `%s`", err, err.Error())
+	}
+}
+
+func TestHashIndexArgsInvalid(t *testing.T) {
+	input := `{}`
+
+	args := new(HashIndexArgs)
+	err := json.Unmarshal([]byte(input), &args)
+	switch err.(type) {
+	case nil:
+		t.Error("Expected error but didn't get one")
+	case *DecodeParamError:
+		break
+	default:
+		t.Errorf("Expected *rpc.DecodeParamError but got %T with message `%s`", err, err.Error())
+	}
+}
+
+func TestHashIndexArgsInvalidHash(t *testing.T) {
+	input := `[7, "0x1"]`
+
+	args := new(HashIndexArgs)
+	err := json.Unmarshal([]byte(input), &args)
+	switch err.(type) {
+	case nil:
+		t.Error("Expected error but didn't get one")
+	case *InvalidTypeError:
+		break
+	default:
+		t.Errorf("Expected *rpc.InvalidTypeError but got %T with message `%s`", err, err.Error())
+	}
+}
+
+func TestHashIndexArgsInvalidIndex(t *testing.T) {
+	input := `["0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b", false]`
+
+	args := new(HashIndexArgs)
+	err := json.Unmarshal([]byte(input), &args)
+	switch err.(type) {
+	case nil:
+		t.Error("Expected error but didn't get one")
+	case *InvalidTypeError:
+		break
+	default:
+		t.Errorf("Expected *rpc.InvalidTypeError but got %T with message `%s`", err, err.Error())
+	}
+}
+
 func TestSubmitWorkArgs(t *testing.T) {
 	input := `["0x0000000000000001", "0x1234567890abcdef1234567890abcdef", "0xD1GE5700000000000000000000000000"]`
 	expected := new(SubmitWorkArgs)