diff --git a/Project.toml b/Project.toml
index a1b711b..6488c5e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "msghandler"
 uuid = "f2724d33-f338-4a57-b9f8-1be882570d10"
-version = "1.2.0"
+version = "1.2.1"
 authors = ["narawat <narawat@gmail.com>"]
 
 [deps]
diff --git a/src/msghandler.jl b/src/msghandler.jl
index 92c595b..b3cd123 100644
--- a/src/msghandler.jl
+++ b/src/msghandler.jl
@@ -639,7 +639,7 @@ function _serialize_data(data::Any, payload_type::String)
     json_obj = JSON.parse(json_str_2)
   """
 
-  if data <: AbstractString  # Text data - convert to UTF-8 bytes
+  if payload_type == "text"  # Text data - convert to UTF-8 bytes
     @info "msghandler _serialize_data() 1" @__LINE__
     data_bytes = Vector{UInt8}(string(data)) # Convert string to UTF-8 bytes
     return data_bytes