diff --git a/target_clickhouse/sinks.py b/target_clickhouse/sinks.py
index b3f9c3a..5b73b1d 100644
--- a/target_clickhouse/sinks.py
+++ b/target_clickhouse/sinks.py
@@ -177,6 +177,8 @@ def _pre_validate_for_string_type(self, record: dict) -> dict:
             expected_type = self.schema.get("properties", {}).get(key, {}).get("type")
             if expected_type is None:
                 continue
+            if not isinstance(expected_type, list):
+                expected_type = [expected_type]
             if "string" in expected_type and not isinstance(value, str):
                 # Convert the value to string if it's not already a string.
                 record[key] = (