diff --git a/requirements.txt b/requirements.txt
index fbdd29cd..3aa4fe82 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 # This is used to build the CI test environment and so Github can track dependencies.
-xarray==2024.3.0
+xarray==2025.1.2
 pandas==2.2.3
 numpy==1.26.4
 matplotlib==3.10.1
@@ -15,3 +15,4 @@ h5netcdf==1.6.1
 impactlab-tools==0.6.0
 p_tqdm==1.4.2
 pyarrow==19.0.1
+numcodecs==0.15.1
diff --git a/src/dscim/preprocessing/input_damages.py b/src/dscim/preprocessing/input_damages.py
index e55f6bb0..a5d71a35 100644
--- a/src/dscim/preprocessing/input_damages.py
+++ b/src/dscim/preprocessing/input_damages.py
@@ -715,6 +715,7 @@ def prep_mortality_damages(
 
     # longest-string gcm has to be processed first so the coordinate is the right str length
     gcms = sorted(gcms, key=len, reverse=True)
+    max_gcm_len = len(gcms[0])
 
     if mortality_version == 0:
         scaling_deaths = "epa_scaled"
@@ -808,6 +809,8 @@ def prep(
             if damages[v].dtype == object:
                 damages[v] = damages[v].astype("unicode")
 
+        damages["gcm"] = damages["gcm"].astype("U" + str(max_gcm_len))
+
         if i == 0:
             damages.to_zarr(
                 f"{outpath}/impacts-darwin-montecarlo-damages-v{mortality_version}.zarr",
diff --git a/tests/test_main_recipe.py b/tests/test_main_recipe.py
index e69c3958..28b0b3e2 100644
--- a/tests/test_main_recipe.py
+++ b/tests/test_main_recipe.py
@@ -258,11 +258,11 @@ def test_weitzman_min(menu_instance):
     diff = censored_values_slower[0:index] - censored_values[0:index]
     assert all(x > 0 for x in diff)
     as_share = menu_instance.weitzman_min(
-        [20, 50, 100], [5, 30, 60], as_share
+        np.array([20, 50, 100]), np.array([5, 30, 60]), as_share
     )  # the first value only should be censored
     assert as_share[0] != 5 and [as_share[1], as_share[2]] == [30, 60]
     all_cons = menu_instance.weitzman_min(
-        [20, 50, 100], [5, 30, 60], all_cons
+        np.array([20, 50, 100]), np.array([5, 30, 60]), all_cons
     )  # all values should be changed
     assert all([x != 0 for x in all_cons - [5, 30, 60]])