diff --git a/dvc/utils/hydra.py b/dvc/utils/hydra.py
index 281ef0c95..45fb759fd 100644
--- a/dvc/utils/hydra.py
+++ b/dvc/utils/hydra.py
@@ -86,8 +86,13 @@ def to_hydra_overrides(path_overrides):
 def get_hydra_sweeps(path_overrides):
     merged_overrides = []
     for path, overrides in path_overrides.items():
+        # `.` is reserved character in hydra syntax
+        # _merge_ is required to support sweeps across multiple files.
         merged_overrides.extend(
-            [f"{path}___{override}" for override in overrides]
+            [
+                f"{path.replace('.', '_')}_merge_{override}"
+                for override in overrides
+            ]
         )
 
     hydra_overrides = to_hydra_overrides(merged_overrides)
@@ -103,7 +108,7 @@ def get_hydra_sweeps(path_overrides):
     for split in splits:
         sweep_overrides = defaultdict(list)
         for merged_override in split:
-            path, override = merged_override.split("___")
-            sweep_overrides[path].append(override)
+            path, override = merged_override.split("_merge_")
+            sweep_overrides[path.replace("_", ".")].append(override)
         sweeps.append(dict(sweep_overrides))
     return sweeps
diff --git a/tests/func/utils/test_hydra.py b/tests/func/utils/test_hydra.py
index f7942fa84..8d1c0d092 100644
--- a/tests/func/utils/test_hydra.py
+++ b/tests/func/utils/test_hydra.py
@@ -183,6 +183,13 @@ def test_compose_and_dump(tmp_dir, suffix, overrides, expected):
 @pytest.mark.parametrize(
     "overrides, expected",
     [
+        (
+            {"params.yaml": ["defaults/foo=1,2"]},
+            [
+                {"params.yaml": ["defaults/foo=1"]},
+                {"params.yaml": ["defaults/foo=2"]},
+            ],
+        ),
         (
             {"params.yaml": ["foo=1,2", "bar=3,4"]},
             [