diff --git a/pyproject.toml b/pyproject.toml
index 302a8657b9..262389ee98 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ filterwarnings = "ignore"
 [tool.ruff]
 line-length = 79
 
-ignore = [
+lint.ignore = [
     # line-length is handled by black
     "E501",
 
diff --git a/requirements/requirements-docs.txt b/requirements/requirements-docs.txt
index 4e0fc592ae..645e7632c3 100644
--- a/requirements/requirements-docs.txt
+++ b/requirements/requirements-docs.txt
@@ -3,6 +3,7 @@ ipykernel~=6.5
 nbconvert~=6.5.1
 nbsphinx~=0.8.8
 notedown
+lxml~=5.1.0
 pytest-runner~=2.11
 recommonmark
 sphinx~=4.0
diff --git a/src/gluonts/dataset/repository/_ett_small.py b/src/gluonts/dataset/repository/_ett_small.py
index 757f595d96..8370d4feaa 100644
--- a/src/gluonts/dataset/repository/_ett_small.py
+++ b/src/gluonts/dataset/repository/_ett_small.py
@@ -39,7 +39,7 @@ def generate_ett_small_dataset(
         dfs.append(df)
 
     test = []
-    for df in dfs:
+    for region, df in enumerate(dfs):
         start = pd.Period(df["date"][0], freq=freq)
         for col in df.columns:
             if col in ["date"]:
@@ -47,13 +47,13 @@ def generate_ett_small_dataset(
             test.append(
                 {
                     "start": start,
-                    "item_id": col,
+                    "item_id": f"{col}_{region}",
                     "target": df[col].values,
                 }
             )
 
     train = []
-    for df in dfs:
+    for region, df in enumerate(dfs):
         start = pd.Period(df["date"][0], freq=freq)
         for col in df.columns:
             if col in ["date"]:
@@ -61,7 +61,7 @@ def generate_ett_small_dataset(
             train.append(
                 {
                     "start": start,
-                    "item_id": col,
+                    "item_id": f"{col}_{region}",
                     "target": df[col].values[:-prediction_length],
                 }
             )
diff --git a/src/gluonts/dataset/repository/_m5.py b/src/gluonts/dataset/repository/_m5.py
index cea591dc5f..6d9e6b80a8 100644
--- a/src/gluonts/dataset/repository/_m5.py
+++ b/src/gluonts/dataset/repository/_m5.py
@@ -113,7 +113,11 @@ def generate_m5_dataset(
     ]
 
     # Build target series
-    train_ids = sales_train_validation["item_id"]
+    train_ids = (
+        sales_train_validation["item_id"].str
+        + "_"
+        + sales_train_validation["store_id"].str
+    )
     train_df = sales_train_validation.drop(
         ["id", "item_id", "dept_id", "cat_id", "store_id", "state_id"],
         axis=1,
diff --git a/src/gluonts/json.py b/src/gluonts/json.py
index 58e9e1fd8a..c92ce4f8cc 100644
--- a/src/gluonts/json.py
+++ b/src/gluonts/json.py
@@ -26,7 +26,8 @@
 character if set to `True`.
 """
 
-__all__ = [  # noqa
+# ruff: noqa: F822
+__all__ = [
     "variant",
     "dump",
     "dumps",