diff --git a/nitransforms/tests/test_base.py b/nitransforms/tests/test_base.py
index 4940ac4f..8422ca10 100644
--- a/nitransforms/tests/test_base.py
+++ b/nitransforms/tests/test_base.py
@@ -113,7 +113,8 @@ def _to_hdf5(klass, x5_root):
     gii = nb.gifti.GiftiImage(
         darrays=[
             nb.gifti.GiftiDataArray(
-                data=xfm.reference.ndcoords, intent=nb.nifti1.intent_codes["pointset"]
+                data=xfm.reference.ndcoords.astype("float32"),
+                intent=nb.nifti1.intent_codes["pointset"],
             )
         ]
     )