diff --git a/pyproject.toml b/pyproject.toml
index 59f0a201..023ba973 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -51,7 +51,7 @@ symmetry = ["moyopy>=0.7.8"]
 mace = ["mace-torch>=0.3.15"]
 mattersim = ["mattersim>=0.1.2"]
 metatomic = ["metatomic-torch>=0.1.3", "metatrain[pet]>=2025.12"]
-orb = ["orb-models>=0.5.2"]
+orb = ["orb-models>=0.5.2,<0.6.0"]
 sevenn = ["sevenn[torchsim]>=0.12.1"]
 graphpes = ["graph-pes>=0.1", "mace-torch>=0.3.12"]
 nequip = ["nequip>=0.17.0"]