diff --git a/Libraries/LibWeb/CSS/SelectorEngine.cpp b/Libraries/LibWeb/CSS/SelectorEngine.cpp
index 66fa7649b7b..efe08cfb15a 100644
--- a/Libraries/LibWeb/CSS/SelectorEngine.cpp
+++ b/Libraries/LibWeb/CSS/SelectorEngine.cpp
@@ -303,6 +303,7 @@ static inline bool matches_attribute(CSS::Selector::SimpleSelector::Attribute co
             // See: https://html.spec.whatwg.org/multipage/semantics-other.html#case-sensitivity-of-selectors
             if (element.document().is_html_document()
                 && element.namespace_uri() == Namespace::HTML
+                && attribute.qualified_name.namespace_type == CSS::Selector::SimpleSelector::QualifiedName::NamespaceType::Default
                 && attribute_name.is_one_of(
                     HTML::AttributeNames::accept, HTML::AttributeNames::accept_charset, HTML::AttributeNames::align,
                     HTML::AttributeNames::alink, HTML::AttributeNames::axis, HTML::AttributeNames::bgcolor, HTML::AttributeNames::charset,
diff --git a/Tests/LibWeb/Text/expected/wpt-import/css/selectors/attribute-selectors/attribute-case/semantics.txt b/Tests/LibWeb/Text/expected/wpt-import/css/selectors/attribute-selectors/attribute-case/semantics.txt
index f47af8ef6c2..e8148608463 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/css/selectors/attribute-selectors/attribute-case/semantics.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/css/selectors/attribute-selectors/attribute-case/semantics.txt
@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 955 tests
 
-926 Pass
-29 Fail
+934 Pass
+21 Fail
 Pass	[foo='BAR'] /* sanity check (match) */ <div foo="BAR"> in standards mode
 Pass	[foo='BAR'] /* sanity check (match) */ <div foo="BAR"> with querySelector in standards mode
 Pass	[foo='bar'] /* sanity check (match) */ <div foo="bar"> in standards mode
@@ -115,10 +115,10 @@ Pass	[id^='a'] /* sanity check (no match) */ <div id="AB"> in standards mode
 Pass	[id^='a'] /* sanity check (no match) */ <div id="AB"> with querySelector in standards mode
 Pass	[id$='A'] <div id="xa"> in standards mode
 Pass	[id$='A'] <div id="xa"> with querySelector in standards mode
-Fail	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> in standards mode
-Fail	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> with querySelector in standards mode
-Fail	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in standards mode
-Fail	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> with querySelector in standards mode
+Pass	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> in standards mode
+Pass	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> with querySelector in standards mode
+Pass	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in standards mode
+Pass	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> with querySelector in standards mode
 Pass	@namespace x 'http://www.w3.org/XML/1998/namespace'; [x|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in standards mode
 Pass	[foo='' i] <div foo="BAR"> in standards mode
 Pass	[foo='' i] <div foo="BAR"> with querySelector in standards mode
@@ -436,10 +436,10 @@ Pass	[id^='a'] /* sanity check (no match) */ <div id="AB"> in quirks mode
 Pass	[id^='a'] /* sanity check (no match) */ <div id="AB"> with querySelector in quirks mode
 Pass	[id$='A'] <div id="xa"> in quirks mode
 Pass	[id$='A'] <div id="xa"> with querySelector in quirks mode
-Fail	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> in quirks mode
-Fail	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> with querySelector in quirks mode
-Fail	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in quirks mode
-Fail	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> with querySelector in quirks mode
+Pass	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> in quirks mode
+Pass	[*|lang='a'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="A"> with querySelector in quirks mode
+Pass	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in quirks mode
+Pass	[*|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> with querySelector in quirks mode
 Pass	@namespace x 'http://www.w3.org/XML/1998/namespace'; [x|lang='A'] /* sanity check (no match) */ <div {http://www.w3.org/XML/1998/namespace}lang="a"> in quirks mode
 Pass	[foo='' i] <div foo="BAR"> in quirks mode
 Pass	[foo='' i] <div foo="BAR"> with querySelector in quirks mode