From a19a84e7a891318cccc798fcf28537eaaebeff89 Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sun, 22 Jun 2025 10:33:59 -0400
Subject: [PATCH] Update src/fastmcp/client/client.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 src/fastmcp/client/client.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/fastmcp/client/client.py b/src/fastmcp/client/client.py
index c0e78a2d5..952a94796 100644
--- a/src/fastmcp/client/client.py
+++ b/src/fastmcp/client/client.py
@@ -533,7 +533,7 @@ class Client(Generic[ClientTransportT]):
                     serialized_arguments[key] = value
                 else:
                     # Use pydantic_core.to_json for consistent serialization
-                    serialized_arguments[key] = pydantic_core.to_json(value).decode()
+                    serialized_arguments[key] = pydantic_core.to_json(value).decode('utf-8')
 
         result = await self.session.get_prompt(
             name=name, arguments=serialized_arguments