diff --git a/pyproject.toml b/pyproject.toml
index 73c94bf..6dd90c1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,7 +39,7 @@ scripts.mergecal = "mergecal.cli:app"
 
 [dependency-groups]
 dev = [
-  "pytest>=8,<9",
+  "pytest>=9,<10",
   "pytest-cov>=6,<7",
 ]
 docs = [