diff --git a/apax/train/metrics.py b/apax/train/metrics.py
index 151cfe68..e5067b0f 100644
--- a/apax/train/metrics.py
+++ b/apax/train/metrics.py
@@ -9,7 +9,13 @@
 log = logging.getLogger(__name__)
 
 
-class RootAverage(metrics.Average):
+class Averagefp64(metrics.Average):
+    @classmethod
+    def empty(cls) -> metrics.Metric:
+        return cls(total=jnp.array(0, jnp.float64), count=jnp.array(0, jnp.int64))
+
+
+class RootAverage(Averagefp64):
     """
     Modifies the `compute` method of `metrics.Average` to obtain the root of the average.
     Meant to be used with `mse_fn`.
@@ -59,7 +65,7 @@ def make_single_metric(key: str, reduction: str) -> metrics.Average:
     if reduction == "rmse":
         metric = RootAverage
     else:
-        metric = metrics.Average
+        metric = Averagefp64
 
     reduction_fn = reduction_fns[reduction]
     reduction_fn = partial(reduction_fn, key=key)