diff --git a/tests/unit/style/size_of.rs b/tests/unit/style/size_of.rs
index 3f15a8d24e4..075ea58e078 100644
--- a/tests/unit/style/size_of.rs
+++ b/tests/unit/style/size_of.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use selectors::parser::SelectorParseError;
 use style::invalidation::element::invalidation_map::Dependency;
 use style::properties;
 
@@ -12,3 +13,9 @@ size_of_test!(test_size_of_property_declaration, properties::PropertyDeclaration
 // This is huge, but we allocate it on the stack and then never move it,
 // we only pass `&mut SourcePropertyDeclaration` references around.
 size_of_test!(test_size_of_parsed_declaration, properties::SourcePropertyDeclaration, 576);
+
+size_of_test!(test_size_of_selector_parse_error_with_unit, SelectorParseError<()>, 40);
+size_of_test!(test_size_of_style_parse_error, ::style_traits::StyleParseError, 80);
+size_of_test!(test_size_of_value_parse_error, ::style_traits::ValueParseError, 40);
+size_of_test!(test_size_of_declaration_parse_error, ::style_traits::PropertyDeclarationParseError, 72);
+size_of_test!(test_size_of_style_traits_parse_error, ::style_traits::ParseError, 96);