diff --git a/pandera/backends/pandas/array.py b/pandera/backends/pandas/array.py
index de7b10750..b913ad00c 100644
--- a/pandera/backends/pandas/array.py
+++ b/pandera/backends/pandas/array.py
@@ -329,11 +329,13 @@ def set_default(self, check_obj, schema):
         if is_field(check_obj) and not isinstance(
             check_obj.dtype, pd.SparseDtype
         ):
-            check_obj.fillna(schema.default, inplace=True)
+            check_obj = check_obj.fillna(schema.default)
         elif not is_field(check_obj) and not isinstance(
             check_obj[schema.name].dtype, pd.SparseDtype
         ):
-            check_obj[schema.name].fillna(schema.default, inplace=True)
+            check_obj[schema.name] = check_obj[schema.name].fillna(
+                schema.default
+            )
 
         return check_obj