diff --git a/siuba/dply/verbs.py b/siuba/dply/verbs.py
index c7eba6fb..f138df8d 100644
--- a/siuba/dply/verbs.py
+++ b/siuba/dply/verbs.py
@@ -133,9 +133,16 @@ def _mutate_cols(__data, args, kwargs):
         if not isinstance(res_arg, pd.DataFrame):
             raise NotImplementedError("Only across() can be used as positional argument.")
 
+        # unpack result
+        is_scalar = len(res_arg) == 1
+
         for col_name, col_ser in res_arg.items():
             # need to put on the frame so subsequent args, kwargs can use
-            df_tmp[col_name] = col_ser
+            if is_scalar:
+                df_tmp.loc[:, col_name] = col_ser.iloc[0]
+            else:
+                df_tmp.loc[:, col_name] = col_ser.array
+
             result_names[col_name] = True
 
     for col_name, expr in kwargs.items():
diff --git a/siuba/sql/across.py b/siuba/sql/across.py
index 0b7aeedb..59a2ba5e 100644
--- a/siuba/sql/across.py
+++ b/siuba/sql/across.py
@@ -1,6 +1,8 @@
 from siuba.dply.across import across, _get_name_template, _across_setup_fns, ctx_verb_data, ctx_verb_window
 from siuba.dply.tidyselect import var_select, var_create
-from siuba.siu import FormulaContext, Call
+from siuba.siu import FormulaContext, Call, FormulaArg
+from siuba.siu.calls import str_to_getitem_call
+from siuba.siu.visitors import CallListener
 
 from .backend import LazyTbl
 from .utils import _sql_select, _sql_column_collection
@@ -8,6 +10,18 @@
 from sqlalchemy import sql
 
 
+class ReplaceFx(CallListener):
+    def __init__(self, replacement):
+        self.replacement = replacement
+
+    def exit(self, node):
+        res = super().exit(node)
+        if isinstance(res, FormulaArg):
+            return str_to_getitem_call(self.replacement)
+
+        return res
+
+
 @across.register(LazyTbl)
 def _across_lazy_tbl(__data: LazyTbl, cols, fns, names: "str | None" = None) -> LazyTbl:
     raise NotImplementedError(
@@ -49,20 +63,23 @@ def _across_sql_cols(
             old_name = new_name
 
         crnt_col = __data[old_name]
-        context = FormulaContext(Fx=crnt_col, _=__data)
+        #context = FormulaContext(Fx=crnt_col, _=__data)
 
         # iterate over functions ----
         for fn_name, fn in fns_map.items():
             fmt_pars = {"fn": fn_name, "col": new_name}
 
+            fn_replaced = ReplaceFx(old_name).enter(fn)
             new_call = lazy_tbl.shape_call(
-                fn,
+                fn_replaced,
                 window,
                 verb_name="Across",
                 arg_name = f"function {fn_name} of {len(fns_map)}"
             )
 
-            res = new_call(context)
+            res, windows, _ = lazy_tbl.track_call_windows(new_call, __data)
+
+            #res = new_call(context)
             res_name = name_template.format(**fmt_pars)
             results.append(res.label(res_name))
 
diff --git a/siuba/tests/test_verb_across.py b/siuba/tests/test_verb_across.py
index ddad1fd5..6d954524 100644
--- a/siuba/tests/test_verb_across.py
+++ b/siuba/tests/test_verb_across.py
@@ -172,6 +172,31 @@ def test_across_in_mutate_grouped_equiv_ungrouped(backend, df):
     assert_equal_query2(ungroup(g_res), collect(dst))
 
 
+def test_across_in_mutate_grouped_agg(backend):
+    df = pd.DataFrame({"x": [1, 2, 3], "y": [7, 8, 9], "g": [1, 1, 2]})
+    src = backend.load_df(df)
+    g_src = group_by(src, "g")
+
+    expr_across = across(_, _[_.x, _.y], f_mean)
+    g_res = mutate(g_src, expr_across)
+    dst = mutate(df.groupby("g"), expr_across)
+
+    assert_grouping_names(g_res, ["g"])
+    assert_equal_query2(ungroup(g_res), ungroup(dst))
+
+
+def test_across_in_mutate_grouped_transform(backend):
+    df = pd.DataFrame({"x": [1, 2, 3], "y": [7, 8, 9], "g": [1, 1, 2]})
+    src = backend.load_df(df)
+    g_src = group_by(src, "g")
+
+    expr_across = across(_, _[_.x, _.y], Fx.rank())
+    g_res = mutate(g_src, expr_across)
+    dst = pd.DataFrame({"x": [1., 2, 1], "y": [1., 2, 1], "g": [1, 1, 2]})
+
+    assert_grouping_names(g_res, ["g"])
+    assert_equal_query2(ungroup(g_res), dst)
+
 def test_across_in_summarize(backend, df):
     src = backend.load_df(df)
     res = summarize(src, across(_, _[_.a_x, _.a_y], f_mean))
@@ -207,6 +232,18 @@ def test_across_in_summarize_equiv_ungrouped(backend):
     assert_frame_sort_equal(collected.drop(columns="g"), collect(dst))
 
 
+def test_across_in_summarize_grouped(backend):
+    df = pd.DataFrame({"x": [1, 2, 3], "y": [7, 8, 9], "g": [1, 1, 2]})
+    src = backend.load_df(df)
+    g_src = group_by(src, "g")
+
+    expr_across = across(_, _[_.x, _.y], f_mean)
+    g_res = summarize(g_src, expr_across)
+    dst = pd.DataFrame({"g": [1, 2], "x": [1.5, 3], "y": [7.5, 9]})
+
+    assert_equal_query2(ungroup(g_res), dst)
+
+
 def test_across_in_filter(backend, df):
     src = backend.load_df(df)
     res = filter(src, across(_, _[_.a_x, _.a_y], Fx % 2 > 0))
@@ -227,6 +264,18 @@ def test_across_in_filter_equiv_ungrouped(backend, df):
     assert_equal_query2(g_res.obj, dst)
 
 
+def test_across_in_filter_grouped(backend):
+    df = pd.DataFrame({"x": [1, 2, 3], "y": [7, 8, 9], "g": [1, 1, 2]})
+    src = backend.load_df(df)
+    g_src = group_by(src, "g")
+
+    expr_across = across(_, _[_.x, _.y], Fx >= Fx.mean())
+    g_res = filter(g_src, expr_across)
+    dst = pd.DataFrame({"x": [2, 3], "y": [8, 9], "g": [1, 2]}, index=[1, 2])
+
+    assert_equal_query2(ungroup(g_res), dst)
+
+
 @pytest.mark.parametrize("f", [
     #(arrange),
     (verbs.count),