diff --git a/pyproject.toml b/pyproject.toml
index e2b8164..d799aed 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ requires-python = ">=3.11"
 dependencies = ["pyyaml>=6.0", "jsonschema>=4.0"]
 
 [project.optional-dependencies]
-dev = ["pytest>=7.0", "hypothesis>=6.0", "mypy>=1.10", "mcp>=0.1"]
+dev = ["pytest>=7.0", "hypothesis>=6.155.6", "mypy>=1.10", "mcp>=0.1"]
 mcp = ["mcp>=0.1"]
 # Install only the router + ontology layer (no conductor OS, no jsonschema):
 #   pip install conductor[router-only]