diff --git a/google/cloud/bigtable/data/_async/client.py b/google/cloud/bigtable/data/_async/client.py
index 639311e6f..fa8a1874f 100644
--- a/google/cloud/bigtable/data/_async/client.py
+++ b/google/cloud/bigtable/data/_async/client.py
@@ -951,12 +951,11 @@ async def mutate_row(
         )
         _validate_timeouts(operation_timeout, attempt_timeout)
 
-        if mutations and not isinstance(mutations, list):
-            mutations = [mutations]
-        if not mutations:
+        mutations_list = mutations if isinstance(mutations, list) else [mutations]
+        if not mutations_list:
             raise ValueError("No mutations provided")
 
-        if all(mutation.is_idempotent() for mutation in mutations):
+        if all(mutation.is_idempotent() for mutation in mutations_list):
             # mutations are all idempotent and safe to retry
             predicate = retries.if_exception_type(
                 core_exceptions.DeadlineExceeded,
@@ -990,7 +989,7 @@ def on_error_fn(exc):
         # trigger rpc
         await deadline_wrapped(
             row_key=row_key.encode("utf-8") if isinstance(row_key, str) else row_key,
-            mutations=[mutation._to_pb() for mutation in mutations],
+            mutations=[mutation._to_pb() for mutation in mutations_list],
             table_name=self.table_name,
             app_profile_id=self.app_profile_id,
             timeout=attempt_timeout,
diff --git a/google/cloud/bigtable/data/read_modify_write_rules.py b/google/cloud/bigtable/data/read_modify_write_rules.py
index dd1399510..f43dbe79f 100644
--- a/google/cloud/bigtable/data/read_modify_write_rules.py
+++ b/google/cloud/bigtable/data/read_modify_write_rules.py
@@ -69,7 +69,7 @@ def __init__(self, family: str, qualifier: bytes | str, append_value: bytes | st
         super().__init__(family, qualifier)
         self.append_value = append_value
 
-    def _to_dict(self) -> dict[str, str | bytes]:
+    def _to_dict(self) -> dict[str, str | bytes | int]:
         return {
             "family_name": self.family,
             "column_qualifier": self.qualifier,