diff --git a/pygmtsar/pygmtsar/Stack_multilooking.py b/pygmtsar/pygmtsar/Stack_multilooking.py
index 1fbbbbb2..f39140cf 100644
--- a/pygmtsar/pygmtsar/Stack_multilooking.py
+++ b/pygmtsar/pygmtsar/Stack_multilooking.py
@@ -76,9 +76,10 @@ def decimator(da):
             warnings.filterwarnings('ignore')
             warnings.filterwarnings('ignore', module='dask')
             warnings.filterwarnings('ignore', module='dask.core')
-            # iunstack data if needed
+            # unstack data if needed
             if 'stack' in da.dims:
-                da = da.unstack('stack')
+                # .unstack() is too slow on lazy grids in some of Xarray/Dask versions
+                da = da.compute().unstack('stack')
             # workaround for Google Colab when we cannot save grids with x,y coordinate names
             # also supports geographic coordinates
             yname = [varname for varname in ['y', 'lat', 'a'] if varname in da.dims][0]