diff --git a/xarray/core/groupby.py b/xarray/core/groupby.py
index e97499f06b4..151ef844f44 100644
--- a/xarray/core/groupby.py
+++ b/xarray/core/groupby.py
@@ -312,7 +312,7 @@ def __init__(
             if not hashable(group):
                 raise TypeError(
                     "`group` must be an xarray.DataArray or the "
-                    "name of an xarray variable or dimension."
+                    "name of an xarray variable or dimension. "
                     f"Received {group!r} instead."
                 )
             group = obj[group]