diff --git a/components/style/properties/cascade.rs b/components/style/properties/cascade.rs
index 3921a4034ed..06db99fd1cc 100644
--- a/components/style/properties/cascade.rs
+++ b/components/style/properties/cascade.rs
@@ -890,7 +890,6 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
             return;
         }
 
-        let use_document_fonts = static_prefs::pref!("browser.display.use_document_fonts") != 0;
         let builder = &mut self.context.builder;
         let (default_font_type, prioritize_user_fonts) = {
             let font = builder.get_font().gecko();
@@ -905,22 +904,23 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
                 return;
             }
 
-            let generic = font.mFont.family.families.single_generic().unwrap_or(GenericFontFamily::None);
             let default_font_type = unsafe {
-                bindings::Gecko_nsStyleFont_ComputeDefaultFontType(
+                bindings::Gecko_nsStyleFont_ComputeFallbackFontTypeForLanguage(
                     builder.device.document(),
-                    generic,
                     font.mLanguage.mRawPtr,
                 )
             };
 
+            let use_document_fonts = static_prefs::pref!("browser.display.use_document_fonts") != 0;
+
             // We prioritize user fonts over document fonts if the pref is set,
             // and we don't have a generic family already (or we're using
             // cursive or fantasy, since they're ignored, see bug 789788), and
             // we have a generic family to actually replace it with.
-            let prioritize_user_fonts = !use_document_fonts &&
+            let prioritize_user_fonts =
+                !use_document_fonts &&
                 default_font_type != GenericFontFamily::None &&
-                !generic.valid_for_user_font_prioritization();
+                font.mFont.family.families.needs_user_font_prioritization();
 
             if !prioritize_user_fonts && default_font_type == font.mFont.family.families.fallback {
                 // Nothing to do.
diff --git a/components/style/values/computed/font.rs b/components/style/values/computed/font.rs
index ab6755d0951..33c2dc469ca 100644
--- a/components/style/values/computed/font.rs
+++ b/components/style/values/computed/font.rs
@@ -627,12 +627,20 @@ impl FontFamilyList {
         self.list = crate::ArcSlice::from_iter(new_list.into_iter());
     }
 
+    /// Returns whether we need to prioritize user fonts.
+    pub (crate) fn needs_user_font_prioritization(&self) -> bool {
+        self.iter().next().map_or(true, |f| match f {
+            SingleFontFamily::Generic(f) => !f.valid_for_user_font_prioritization(),
+            _ => true,
+        })
+    }
+
     /// Return the generic ID if it is a single generic font
     pub fn single_generic(&self) -> Option<GenericFontFamily> {
         let mut iter = self.iter();
         if let Some(SingleFontFamily::Generic(f)) = iter.next() {
             if iter.next().is_none() {
-                return Some(f.clone());
+                return Some(*f);
             }
         }
         None