diff --git a/pyproject.toml b/pyproject.toml
index cec96b76b..7ddf547f2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ requires = [
     "types-requests",
     "types-psutil",
     "importlib_resources>=1.4;python_version<'3.9'",
-    "ruamel.yaml>=0.16.0,<0.18",
+    "ruamel.yaml>=0.16.0,<0.19",
     "schema-salad>=8.7,<9",
     "cwl-utils>=0.32",
     "toml",