diff --git a/servo/components/style/values/computed/page.rs b/servo/components/style/values/computed/page.rs
index 524f6ba468e1..27b16d0af15a 100644
--- a/servo/components/style/values/computed/page.rs
+++ b/servo/components/style/values/computed/page.rs
@@ -36,16 +36,14 @@ impl ToComputedValue for specified::PageSize {
     fn to_computed_value(&self, ctx: &Context) -> Self::ComputedValue {
         match &*self {
             Self::Size(s) => PageSize::Size(s.to_computed_value(ctx)),
-            Self::PaperSizeAndOrientation(p, Orientation::Landscape) => PageSize::Size(Size2D {
+            Self::PaperSize(p, Orientation::Landscape) => PageSize::Size(Size2D {
                 width: p.long_edge().to_computed_value(ctx),
                 height: p.short_edge().to_computed_value(ctx),
             }),
-            Self::PaperSizeAndOrientation(p, Orientation::Portrait) | Self::PaperSize(p) => {
-                PageSize::Size(Size2D {
-                    width: p.short_edge().to_computed_value(ctx),
-                    height: p.long_edge().to_computed_value(ctx),
-                })
-            },
+            Self::PaperSize(p, Orientation::Portrait) => PageSize::Size(Size2D {
+                width: p.short_edge().to_computed_value(ctx),
+                height: p.long_edge().to_computed_value(ctx),
+            }),
             Self::Orientation(o) => PageSize::Orientation(*o),
             Self::Auto => PageSize::Auto,
         }
diff --git a/servo/components/style/values/generics/page.rs b/servo/components/style/values/generics/page.rs
index 6f5617104910..1de1a8e912c1 100644
--- a/servo/components/style/values/generics/page.rs
+++ b/servo/components/style/values/generics/page.rs
@@ -94,22 +94,25 @@ pub enum Orientation {
     Landscape,
 }
 
+#[inline]
+fn is_portrait(orientation: &Orientation) -> bool {
+    *orientation == Orientation::Portrait
+}
+
 /// Page size property
 ///
 /// https://drafts.csswg.org/css-page-3/#page-size-prop
 #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
 #[repr(C, u8)]
 pub enum GenericPageSize<S> {
-    /// Page dimensions.
-    Size(S),
-    /// Paper size with no orientation.
-    PaperSize(PaperSize),
-    /// An orientation with no size.
-    Orientation(Orientation),
-    /// Paper size by name, with an orientation.
-    PaperSizeAndOrientation(PaperSize, Orientation),
     /// `auto` value.
     Auto,
+    /// Page dimensions.
+    Size(S),
+    /// An orientation with no size.
+    Orientation(Orientation),
+    /// Paper size by name
+    PaperSize(PaperSize, #[css(skip_if = "is_portrait")] Orientation),
 }
 
 pub use self::GenericPageSize as PageSize;
diff --git a/servo/components/style/values/specified/page.rs b/servo/components/style/values/specified/page.rs
index 81684e114a34..4d96b5326899 100644
--- a/servo/components/style/values/specified/page.rs
+++ b/servo/components/style/values/specified/page.rs
@@ -23,15 +23,15 @@ impl Parse for PageSize {
     ) -> Result<Self, ParseError<'i>> {
         // Try to parse as <page-size> [ <orientation> ]
         if let Ok(paper_size) = input.try_parse(PaperSize::parse) {
-            if let Ok(orientation) = input.try_parse(Orientation::parse) {
-                return Ok(PageSize::PaperSizeAndOrientation(paper_size, orientation));
-            }
-            return Ok(PageSize::PaperSize(paper_size));
+            let orientation = input
+                .try_parse(Orientation::parse)
+                .unwrap_or(Orientation::Portrait);
+            return Ok(PageSize::PaperSize(paper_size, orientation));
         }
         // Try to parse as <orientation> [ <page-size> ]
         if let Ok(orientation) = input.try_parse(Orientation::parse) {
             if let Ok(paper_size) = input.try_parse(PaperSize::parse) {
-                return Ok(PageSize::PaperSizeAndOrientation(paper_size, orientation));
+                return Ok(PageSize::PaperSize(paper_size, orientation));
             }
             return Ok(PageSize::Orientation(orientation));
         }