diff --git a/conda-env/dev.yml b/conda-env/dev.yml
index 597d568a8..78874f829 100644
--- a/conda-env/dev.yml
+++ b/conda-env/dev.yml
@@ -28,6 +28,7 @@ dependencies:
     - regionmask=0.9.0
     - rasterio=1.3.6
     - shapely=2.0.1
+    - numdifftools
     # ==================
     # Testing
     # ==================