diff --git a/pyproject.toml b/pyproject.toml
index f455522..9390307 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,6 +20,7 @@ dependencies = [
     "scipy==1.13.1",
     "trimesh==3.23.5",
     "pygamer==2.0.7",
+    "rtree==1.0.1",
     "matplotlib==3.5.1",
     "plotly==5.7.0",
     "kaleido==0.2.1",
@@ -33,7 +34,6 @@ dependencies = [
 
 [project.optional-dependencies]
 pbe-standard = [
-    "rtree==1.0.1",
     "numba==0.59.1",
     "meshio==5.3.4",
     "gmsh==4.9.5",