diff --git a/pyproject.toml b/pyproject.toml
index 5bac1a0..48a8d29 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -30,7 +30,8 @@ dependencies = [
     "tqdm",
     "seaborn",
     "nglview",
-    "pillow"
+    "pillow",
+    "numpy-stl"
 ]
 
 # Update the urls once the hosting is set up.