diff --git a/xdas/spectral.py b/xdas/spectral.py
index 55e4089..1aafbcc 100644
--- a/xdas/spectral.py
+++ b/xdas/spectral.py
@@ -72,4 +72,6 @@ def func(x):
     coords[input_dim] = time
     coords[output_dim] = freqs
 
-    return DataArray(data, coords)
+    dims = da.dims + (output_dim,)
+
+    return DataArray(data, coords, dims)