diff --git a/flox/aggregate_flox.py b/flox/aggregate_flox.py
index 4bd9c24a9..03f3c2094 100644
--- a/flox/aggregate_flox.py
+++ b/flox/aggregate_flox.py
@@ -207,7 +207,7 @@ def nansum_of_squares(group_idx, array, *, axis=-1, size=None, fill_value=None,
 
 
 def nanlen(group_idx, array, *args, **kwargs):
-    return sum(group_idx, (notnull(array)).astype(int), *args, **kwargs)
+    return sum(group_idx, (notnull(array)).view(np.int8), *args, **kwargs)
 
 
 def mean(group_idx, array, *, axis=-1, size=None, fill_value=None, dtype=None):
@@ -215,14 +215,16 @@ def mean(group_idx, array, *, axis=-1, size=None, fill_value=None, dtype=None):
         fill_value = 0
     out = sum(group_idx, array, axis=axis, size=size, dtype=dtype, fill_value=fill_value)
     with np.errstate(invalid="ignore", divide="ignore"):
-        out /= nanlen(group_idx, array, size=size, axis=axis, fill_value=0)
+        out /= nanlen(group_idx, array, size=size, axis=axis, fill_value=0, dtype=np.intp)
     return out
 
 
 def nanmean(group_idx, array, *, axis=-1, size=None, fill_value=None, dtype=None):
     if fill_value is None:
         fill_value = 0
-    out = nansum(group_idx, array, size=size, axis=axis, dtype=dtype, fill_value=fill_value)
+    mask = notnull(array)
+    masked = np.where(mask, array, 0)
+    out = sum(group_idx, masked, size=size, axis=axis, dtype=dtype, fill_value=fill_value)
     with np.errstate(invalid="ignore", divide="ignore"):
-        out /= nanlen(group_idx, array, size=size, axis=axis, fill_value=0)
+        out /= sum(group_idx, mask.view(np.int8), size=size, axis=axis, fill_value=0, dtype=np.intp)
     return out