diff --git a/mempalace/mcp_server.py b/mempalace/mcp_server.py
index 6fe8225..48e8031 100644
--- a/mempalace/mcp_server.py
+++ b/mempalace/mcp_server.py
@@ -1689,6 +1689,16 @@ def _restore_stdout():
 
 def main():
     _restore_stdout()
+    # Force UTF-8 on stdio. MCP JSON-RPC is UTF-8, but Python on Windows
+    # defaults stdin/stdout to the system codepage (e.g. cp1251), which
+    # corrupts non-ASCII payloads and surfaces as generic -32000 errors on
+    # Cyrillic/CJK content. See PEP 540.
+    for stream in (sys.stdin, sys.stdout):
+        if hasattr(stream, "reconfigure"):
+            try:
+                stream.reconfigure(encoding="utf-8", errors="replace")
+            except (AttributeError, OSError):
+                pass
     logger.info("MemPalace MCP Server starting...")
     while True:
         try: