diff --git a/astacus/coordinator/plugins/clickhouse/steps.py b/astacus/coordinator/plugins/clickhouse/steps.py
index 62b87ab0..ec7ac514 100644
--- a/astacus/coordinator/plugins/clickhouse/steps.py
+++ b/astacus/coordinator/plugins/clickhouse/steps.py
@@ -518,7 +518,6 @@ def _create_dbs(client: ClickHouseClient) -> Iterator[Awaitable[None]]:
             b"SET allow_experimental_object_type=true",
             b"SET allow_suspicious_codecs=true",
             b"SET allow_suspicious_low_cardinality_types=true",
-            b"SET merge_tree_allow_nullable_key=true",
             # If a table was created with flatten_nested=0, we must be careful to not re-create the
             # table with flatten_nested=1, since this would recreate the table with a different schema.
             # If a table was created with flatten_nested=1, the query in system.tables.create_table_query
diff --git a/tests/integration/coordinator/plugins/clickhouse/test_plugin.py b/tests/integration/coordinator/plugins/clickhouse/test_plugin.py
index 6f8d4bce..a154cfb1 100644
--- a/tests/integration/coordinator/plugins/clickhouse/test_plugin.py
+++ b/tests/integration/coordinator/plugins/clickhouse/test_plugin.py
@@ -147,6 +147,7 @@ async def setup_cluster_content(clients: List[HttpClickHouseClient], use_named_c
         b"SETTINGS allow_experimental_object_type=1"
     )
     # test that we can re-create a table requiring custom merge tree settings.
+    # Unlike other cases, we don't have to SET a global settings because it's merge tree setting.
     await clients[0].execute(
         b"CREATE TABLE default.with_nullable_key (thekey Nullable(UInt32), thedata String) "
         b"ENGINE = ReplicatedMergeTree ORDER BY (thekey) "
diff --git a/tests/unit/coordinator/plugins/clickhouse/test_steps.py b/tests/unit/coordinator/plugins/clickhouse/test_steps.py
index 87e41caf..28ee9920 100644
--- a/tests/unit/coordinator/plugins/clickhouse/test_steps.py
+++ b/tests/unit/coordinator/plugins/clickhouse/test_steps.py
@@ -791,7 +791,6 @@ async def test_creates_all_replicated_databases_and_tables_in_manifest() -> None
         b"SET allow_experimental_object_type=true",
         b"SET allow_suspicious_codecs=true",
         b"SET allow_suspicious_low_cardinality_types=true",
-        b"SET merge_tree_allow_nullable_key=true",
         b"SET flatten_nested=0",
         b"CREATE TABLE db-one.table-uno ...",
         b"CREATE TABLE db-one.table-dos ...",
@@ -850,7 +849,6 @@ async def test_creates_all_replicated_databases_and_tables_in_manifest_with_cust
         b"SET allow_experimental_object_type=true",
         b"SET allow_suspicious_codecs=true",
         b"SET allow_suspicious_low_cardinality_types=true",
-        b"SET merge_tree_allow_nullable_key=true",
         b"SET flatten_nested=0",
         b"CREATE TABLE db-one.table-uno ...",
         b"CREATE TABLE db-one.table-dos ...",