diff --git a/pyiceberg/schema.py b/pyiceberg/schema.py
index fd60eb8f94..a79b3ae95f 100644
--- a/pyiceberg/schema.py
+++ b/pyiceberg/schema.py
@@ -1697,7 +1697,7 @@ def _(file_type: BinaryType, read_type: IcebergType) -> IcebergType:
 @promote.register(DecimalType)
 def _(file_type: DecimalType, read_type: IcebergType) -> IcebergType:
     if isinstance(read_type, DecimalType):
-        if file_type.precision <= read_type.precision and file_type.scale == file_type.scale:
+        if file_type.precision <= read_type.precision and file_type.scale == read_type.scale:
             return read_type
         else:
             raise ResolveError(f"Cannot reduce precision from {file_type} to {read_type}")
diff --git a/tests/test_schema.py b/tests/test_schema.py
index 93ddc16202..e9282c0f87 100644
--- a/tests/test_schema.py
+++ b/tests/test_schema.py
@@ -68,6 +68,7 @@
     DoubleType(),
     DecimalType(10, 2),
     DecimalType(100, 2),
+    DecimalType(10, 3),
     StringType(),
     DateType(),
     TimeType(),
@@ -878,7 +879,7 @@ def should_promote(file_type: IcebergType, read_type: IcebergType) -> bool:
     if isinstance(file_type, BinaryType) and isinstance(read_type, StringType):
         return True
     if isinstance(file_type, DecimalType) and isinstance(read_type, DecimalType):
-        return file_type.precision <= read_type.precision and file_type.scale == file_type.scale
+        return file_type.precision <= read_type.precision and file_type.scale == read_type.scale
     if isinstance(file_type, FixedType) and isinstance(read_type, UUIDType) and len(file_type) == 16:
         return True
     return False
@@ -1316,6 +1317,15 @@ def test_type_promote_decimal_to_fixed_scale_with_wider_precision(table_v2: Tabl
     assert decimal_type.scale == 1
 
 
+def test_detect_invalid_promotion_decimal_scale_change(table_v2: Table) -> None:
+    # Per the Iceberg spec, decimal scale is fixed; only precision may grow.
+    current_schema = Schema(NestedField(field_id=1, name="aCol", field_type=DecimalType(precision=20, scale=1), required=False))
+    new_schema = Schema(NestedField(field_id=1, name="aCol", field_type=DecimalType(precision=22, scale=2), required=False))
+
+    with pytest.raises(ValidationError, match="Cannot change column type: aCol: decimal.20, 1. -> decimal.22, 2."):
+        _ = UpdateSchema(transaction=Transaction(table_v2), schema=current_schema).union_by_name(new_schema)._apply()
+
+
 def test_add_nested_structs(primitive_fields: NestedField, table_v2: Table) -> None:
     schema = Schema(
         NestedField(