diff --git a/posthog/clickhouse/property_groups.py b/posthog/clickhouse/property_groups.py
index 418a3c47a6867..89af85e125741 100644
--- a/posthog/clickhouse/property_groups.py
+++ b/posthog/clickhouse/property_groups.py
@@ -29,7 +29,7 @@ def get_alter_table_statements(self, name: str) -> Iterable[str]:
         definition = self.__groups[name]
         return [
             f"ALTER TABLE {self.__table} ON CLUSTER {self.__cluster} ADD COLUMN {column_name} Map(String, String) MATERIALIZED {self.__get_map_expression(definition)} CODEC({definition.codec})",
-            f"ALTER TABLE {self.__table} ON CLUSTER {self.__cluster} ADD INDEX {column_name}_keys_bf mapValues({column_name}) TYPE bloom_filter",
+            f"ALTER TABLE {self.__table} ON CLUSTER {self.__cluster} ADD INDEX {column_name}_keys_bf mapKeys({column_name}) TYPE bloom_filter",
             f"ALTER TABLE {self.__table} ON CLUSTER {self.__cluster} ADD INDEX {column_name}_values_bf mapValues({column_name}) TYPE bloom_filter",
         ]