diff --git a/proxyd/rpc.go b/proxyd/rpc.go
index 902e2669..a2319fd5 100644
--- a/proxyd/rpc.go
+++ b/proxyd/rpc.go
@@ -55,10 +55,10 @@ func (r *RPCRes) MarshalJSON() ([]byte, error) {
 }
 
 type RPCErr struct {
-	Code          int    `json:"code"`
-	Message       string `json:"message"`
-	Data          string `json:"data,omitempty"`
-	HTTPErrorCode int    `json:"-"`
+	Code          int             `json:"code"`
+	Message       string          `json:"message"`
+	Data          json.RawMessage `json:"data,omitempty"`
+	HTTPErrorCode int             `json:"-"`
 }
 
 func (r *RPCErr) Error() string {
diff --git a/proxyd/rpc_test.go b/proxyd/rpc_test.go
index e30fe936..9d6786e7 100644
--- a/proxyd/rpc_test.go
+++ b/proxyd/rpc_test.go
@@ -63,7 +63,7 @@ func TestRPCResJSON(t *testing.T) {
 				Error: &RPCErr{
 					Code:    1234,
 					Message: "test err",
-					Data:    "revert",
+					Data:    []byte(`"revert"`),
 				},
 				ID: []byte("123"),
 			},