diff --git a/pyproject.toml b/pyproject.toml
index 00aff49..843cc8f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ classifiers = [
 dependencies = [
     "mcp>=1.2.0",
     "mcpcat-api==0.1.4",
-    "pydantic>=2.0.0",
+    "pydantic>=2.0.0,<2.12",
     "requests>=2.31.0",
 ]