diff --git a/python/pyspark/sql/connect/column.py b/python/pyspark/sql/connect/column.py
index 26cb1477cee37..7b60adb162966 100644
--- a/python/pyspark/sql/connect/column.py
+++ b/python/pyspark/sql/connect/column.py
@@ -239,24 +239,15 @@ def substr(self, startPos: Union[int, "Column"], length: Union[int, "Column"]) -
 
         if isinstance(length, Column):
             length_expr = length._expr
+            start_expr = startPos._expr  # type: ignore[union-attr]
         elif isinstance(length, int):
             length_expr = LiteralExpression._from_value(length)
-        else:
-            raise PySparkTypeError(
-                error_class="NOT_COLUMN_OR_INT",
-                message_parameters={"arg_name": "length", "arg_type": type(length).__name__},
-            )
-
-        if isinstance(startPos, Column):
-            start_expr = startPos._expr
-        elif isinstance(startPos, int):
             start_expr = LiteralExpression._from_value(startPos)
         else:
             raise PySparkTypeError(
                 error_class="NOT_COLUMN_OR_INT",
-                message_parameters={"arg_name": "startPos", "arg_type": type(startPos).__name__},
+                message_parameters={"arg_name": "length", "arg_type": type(length).__name__},
             )
-
         return Column(UnresolvedFunction("substring", [self._expr, start_expr, length_expr]))
 
     substr.__doc__ = PySparkColumn.substr.__doc__