1 files changed, 3 insertions, 1 deletions
diff --git a/components/script/dom/csssupportsrule.rs b/components/script/dom/csssupportsrule.rs
index 3ac60a00e06..86aedf10864 100644
--- a/components/script/dom/csssupportsrule.rs
+++ b/components/script/dom/csssupportsrule.rs
@@ -61,8 +61,10 @@ impl CSSSupportsRule {
             let global = self.global();
             let win = global.as_window();
             let url = win.Document().url();
+            let quirks_mode = win.Document().quirks_mode();
             let context = ParserContext::new_for_cssom(&url, win.css_error_reporter(), Some(CssRuleType::Supports),
-                                                       LengthParsingMode::Default);
+                                                       LengthParsingMode::Default,
+                                                       quirks_mode);
             let enabled = cond.eval(&context);
             let mut guard = self.cssconditionrule.shared_lock().write();
             let rule = self.supportsrule.write_with(&mut guard);