diff --git a/jsonrpc/jsonrpc_protocol.go b/jsonrpc/jsonrpc_protocol.go
index 4abb1d9..0e029d2 100644
--- a/jsonrpc/jsonrpc_protocol.go
+++ b/jsonrpc/jsonrpc_protocol.go
@@ -155,4 +155,4 @@ type ProgressParams struct {
 }
 
 // ProgressToken is a progress token
-type ProgressToken json.RawMessage
+type ProgressToken string