diff --git a/pyproject.toml b/pyproject.toml
index 4a9f91acf8..7436addb05 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -59,7 +59,7 @@ numpy = {version = ">=1.20.1", optional = true}
 matplotlib = {version = ">=3.3.4", optional = true}
 joblib = {version = ">=1.0.1", optional = true}
 stable-baselines3 = {version = ">=0.11.1", optional = true}
-ray = {extras = ["rllib"], version = ">=1.2.0", optional = true}
+ray = {extras = ["rllib"], version = ">=1.2.0",  optional = true}
 discrete-optimization = {version = ">=0.2.1", optional = true}
 
 [tool.poetry.extras]