diff --git a/pixi.lock b/pixi.lock
index 5721cd2b..19b898f7 100644
--- a/pixi.lock
+++ b/pixi.lock
@@ -9623,8 +9623,8 @@ packages:
   - pydantic
   - xugrid==0.14.3
   - scipy>=1.16.2,<2
+  - sparse>=0.17.0
   - xarray[io,parallel]>=2025.10.1,<2026 ; extra == 'optional'
-  - sparse>=0.17.0 ; extra == 'optional'
   - dask[array]>=2025.10.0,<2026 ; extra == 'optional'
   - pyproj>=3.7.2,<4 ; extra == 'optional'
   - networkx>=3.5,<4 ; extra == 'optional'
diff --git a/pyproject.toml b/pyproject.toml
index a5f80511..7086d51e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,13 +46,13 @@ dependencies = [
     "pydantic",
     "xugrid==0.14.3",
     "scipy>=1.16.2,<2",
+    "sparse>=0.17.0",
 ]
 dynamic = ["version"]
 
 [project.optional-dependencies]
 optional = [
     "xarray[parallel,io]>=2025.10.1,<2026",
-    "sparse>=0.17.0",
     "dask[array]>=2025.10.0,<2026",
     "pyproj>=3.7.2,<4",
     "networkx>=3.5,<4",