diff --git a/src/apify_client/clients/resource_clients/dataset.py b/src/apify_client/clients/resource_clients/dataset.py
index 368eef0b..a84b6f4b 100644
--- a/src/apify_client/clients/resource_clients/dataset.py
+++ b/src/apify_client/clients/resource_clients/dataset.py
@@ -75,9 +75,7 @@ def list_items(
         desc: bool | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_hidden: bool | None = None,
         flatten: list[str] | None = None,
@@ -163,9 +161,7 @@ def iterate_items(
         desc: bool | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_hidden: bool | None = None,
     ) -> Iterator[dict]:
@@ -248,9 +244,7 @@ def download_items(
         delimiter: str | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_header_row: bool | None = None,
         skip_hidden: bool | None = None,
@@ -342,9 +336,7 @@ def get_items_as_bytes(
         delimiter: str | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_header_row: bool | None = None,
         skip_hidden: bool | None = None,
@@ -438,9 +430,7 @@ def stream_items(
         delimiter: str | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_header_row: bool | None = None,
         skip_hidden: bool | None = None,
@@ -625,9 +615,7 @@ async def list_items(
         desc: bool | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_hidden: bool | None = None,
         flatten: list[str] | None = None,
@@ -713,9 +701,7 @@ async def iterate_items(
         desc: bool | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_hidden: bool | None = None,
     ) -> AsyncIterator[dict]:
@@ -799,9 +785,7 @@ async def get_items_as_bytes(
         delimiter: str | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_header_row: bool | None = None,
         skip_hidden: bool | None = None,
@@ -895,9 +879,7 @@ async def stream_items(
         delimiter: str | None = None,
         fields: list[str] | None = None,
         omit: list[str] | None = None,
-        # TODO: change to list[str] only when doing a breaking release
-        # https://github.com/apify/apify-client-python/issues/255
-        unwind: str | list[str] | None = None,
+        unwind: list[str] | None = None,
         skip_empty: bool | None = None,
         skip_header_row: bool | None = None,
         skip_hidden: bool | None = None,
diff --git a/uv.lock b/uv.lock
index 4e297b08..26e7a5df 100644
--- a/uv.lock
+++ b/uv.lock
@@ -23,7 +23,7 @@ wheels = [
 
 [[package]]
 name = "apify-client"
-version = "1.12.2"
+version = "1.12.3"
 source = { editable = "." }
 dependencies = [
     { name = "apify-shared" },