diff --git a/tests/test_coreg/test_biascorr.py b/tests/test_coreg/test_biascorr.py
index fda108a0..f7a61168 100644
--- a/tests/test_coreg/test_biascorr.py
+++ b/tests/test_coreg/test_biascorr.py
@@ -521,10 +521,10 @@ def test_deramp__synthetic(self, fit_args, order: int) -> None:
         deramp = biascorr.Deramp(poly_order=order)
         elev_fit_args = fit_args.copy()
         if isinstance(elev_fit_args["to_be_aligned_elev"], gpd.GeoDataFrame):
-            bias_elev = bias_dem.to_pointcloud(data_column_name="z", subsample=50000).ds
+            bias_elev = bias_dem.to_pointcloud(data_column_name="z", subsample=30000, random_state=42).ds
         else:
             bias_elev = bias_dem
-        deramp.fit(elev_fit_args["reference_elev"], to_be_aligned_elev=bias_elev, subsample=40000, random_state=42)
+        deramp.fit(elev_fit_args["reference_elev"], to_be_aligned_elev=bias_elev, subsample=20000, random_state=42)
 
         # Check high-order fit parameters are the same within 10%
         fit_params = deramp._meta["fit_params"]
@@ -579,7 +579,7 @@ def test_terrainbias__synthetic(self, fit_args) -> None:
         )
         elev_fit_args = fit_args.copy()
         if isinstance(elev_fit_args["to_be_aligned_elev"], gpd.GeoDataFrame):
-            bias_elev = bias_dem.to_pointcloud(data_column_name="z", subsample=20000).ds
+            bias_elev = bias_dem.to_pointcloud(data_column_name="z", subsample=20000, random_state=42).ds
         else:
             bias_elev = bias_dem
         tb.fit(