diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index d67b1c8d23e..9e8cc9bc165 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -418,7 +418,7 @@ impl LayoutThread {
         let font_cache_receiver =
             ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_font_cache_receiver);
 
-        let stylist = Stylist::new(device);
+        let stylist = Stylist::new(device, QuirksMode::NoQuirks);
         let outstanding_web_fonts_counter = Arc::new(AtomicUsize::new(0));
         let ua_stylesheets = &*UA_STYLESHEETS;
         let guard = ua_stylesheets.shared_lock.read();
diff --git a/components/style/build_gecko.rs b/components/style/build_gecko.rs
index 8376587d5ac..8c6ca283aa9 100644
--- a/components/style/build_gecko.rs
+++ b/components/style/build_gecko.rs
@@ -689,6 +689,7 @@ mod bindings {
             "nsCursorImage",
             "nsFont",
             "nsIAtom",
+            "nsCompatibility",
             "nsMediaFeature",
             "nsRestyleHint",
             "nsStyleBackground",
diff --git a/components/style/gecko/data.rs b/components/style/gecko/data.rs
index d8397ddeb93..bf71114da37 100644
--- a/components/style/gecko/data.rs
+++ b/components/style/gecko/data.rs
@@ -9,6 +9,7 @@ use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
 use dom::OpaqueNode;
 use gecko_bindings::bindings::RawServoStyleSet;
 use gecko_bindings::structs::RawGeckoPresContextOwned;
+use gecko_bindings::structs::nsIDocument;
 use gecko_bindings::sugar::ownership::{HasBoxFFI, HasFFI, HasSimpleFFI};
 use media_queries::Device;
 use parking_lot::RwLock;
@@ -56,11 +57,14 @@ impl PerDocumentStyleData {
     /// Create a dummy `PerDocumentStyleData`.
     pub fn new(pres_context: RawGeckoPresContextOwned) -> Self {
         let device = Device::new(pres_context);
+        let quirks_mode = unsafe {
+            (*(*device.pres_context).mDocument.raw::<nsIDocument>()).mCompatMode
+        };
 
         let (new_anims_sender, new_anims_receiver) = channel();
 
         PerDocumentStyleData(AtomicRefCell::new(PerDocumentStyleDataImpl {
-            stylist: Stylist::new(device),
+            stylist: Stylist::new(device, quirks_mode.into()),
             stylesheets: StylesheetSet::new(),
             new_animations_sender: new_anims_sender,
             new_animations_receiver: new_anims_receiver,
diff --git a/components/style/gecko/generated/bindings.rs b/components/style/gecko/generated/bindings.rs
index c365ff677a1..410c35b9b06 100644
--- a/components/style/gecko/generated/bindings.rs
+++ b/components/style/gecko/generated/bindings.rs
@@ -53,6 +53,7 @@ use gecko_bindings::structs::nsChangeHint;
 use gecko_bindings::structs::nsCursorImage;
 use gecko_bindings::structs::nsFont;
 use gecko_bindings::structs::nsIAtom;
+use gecko_bindings::structs::nsCompatibility;
 use gecko_bindings::structs::nsMediaFeature;
 use gecko_bindings::structs::nsRestyleHint;
 use gecko_bindings::structs::nsStyleBackground;
@@ -1949,7 +1950,8 @@ extern "C" {
 }
 extern "C" {
     pub fn Servo_ParseStyleAttribute(data: *const nsACString,
-                                     extra_data: *mut RawGeckoURLExtraData)
+                                     extra_data: *mut RawGeckoURLExtraData,
+                                     quirks_mode: nsCompatibility)
      -> RawServoDeclarationBlockStrong;
 }
 extern "C" {
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 150074770b8..7c2f47b4273 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -336,8 +336,9 @@ impl<'le> fmt::Debug for GeckoElement<'le> {
 impl<'le> GeckoElement<'le> {
     /// Parse the style attribute of an element.
     pub fn parse_style_attribute(value: &str,
-                                 url_data: &UrlExtraData) -> PropertyDeclarationBlock {
-        parse_style_attribute(value, url_data, &RustLogReporter, QuirksMode::NoQuirks)
+                                 url_data: &UrlExtraData,
+                                 quirks_mode: QuirksMode) -> PropertyDeclarationBlock {
+        parse_style_attribute(value, url_data, &RustLogReporter, quirks_mode)
     }
 
     fn flags(&self) -> u32 {
diff --git a/components/style/gecko_bindings/sugar/mod.rs b/components/style/gecko_bindings/sugar/mod.rs
index 1c004c8fcc1..f241c94810b 100644
--- a/components/style/gecko_bindings/sugar/mod.rs
+++ b/components/style/gecko_bindings/sugar/mod.rs
@@ -5,6 +5,7 @@
 //! Rust sugar and convenience methods for Gecko types.
 
 mod ns_com_ptr;
+mod ns_compatibility;
 mod ns_css_shadow_array;
 pub mod ns_css_value;
 mod ns_style_auto_array;
diff --git a/components/style/gecko_bindings/sugar/ns_compatibility.rs b/components/style/gecko_bindings/sugar/ns_compatibility.rs
new file mode 100644
index 00000000000..3fe63391d36
--- /dev/null
+++ b/components/style/gecko_bindings/sugar/ns_compatibility.rs
@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+//! Little helper for `nsCompatibility`.
+
+use context::QuirksMode;
+use gecko_bindings::structs::nsCompatibility;
+
+impl From<nsCompatibility> for QuirksMode {
+    fn from(mode: nsCompatibility) -> QuirksMode {
+        match mode {
+            nsCompatibility::eCompatibility_FullStandards => QuirksMode::NoQuirks,
+            nsCompatibility::eCompatibility_AlmostStandards => QuirksMode::LimitedQuirks,
+            nsCompatibility::eCompatibility_NavQuirks => QuirksMode::Quirks,
+        }
+    }
+}
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index 2cec8f59778..b929777bd2f 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -189,16 +189,17 @@ impl<'a> ExtraStyleData<'a> {
 }
 
 impl Stylist {
-    /// Construct a new `Stylist`, using a given `Device`.  If more members are
-    /// added here, think about whether they should be reset in clear().
+    /// Construct a new `Stylist`, using given `Device` and `QuirksMode`.
+    /// If more members are added here, think about whether they should
+    /// be reset in clear().
     #[inline]
-    pub fn new(device: Device) -> Self {
+    pub fn new(device: Device, quirks_mode: QuirksMode) -> Self {
         let mut stylist = Stylist {
             viewport_constraints: None,
             device: Arc::new(device),
             is_device_dirty: true,
             is_cleared: true,
-            quirks_mode: QuirksMode::NoQuirks,
+            quirks_mode: quirks_mode,
 
             element_map: PerPseudoElementSelectorMap::new(),
             pseudos_map: Default::default(),
@@ -778,6 +779,11 @@ impl Stylist {
         self.viewport_constraints.as_ref()
     }
 
+    /// Returns the Quirks Mode of the document.
+    pub fn quirks_mode(&self) -> QuirksMode {
+        self.quirks_mode
+    }
+
     /// Sets the quirks mode of the document.
     pub fn set_quirks_mode(&mut self, quirks_mode: QuirksMode) {
         // FIXME(emilio): We don't seem to change the quirks mode dynamically
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 0b209849aae..ebe498946c9 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -65,6 +65,7 @@ use style::gecko_bindings::structs::RawGeckoPresContextOwned;
 use style::gecko_bindings::structs::ServoElementSnapshotTable;
 use style::gecko_bindings::structs::URLExtraData;
 use style::gecko_bindings::structs::nsCSSValueSharedList;
+use style::gecko_bindings::structs::nsCompatibility;
 use style::gecko_bindings::structs::nsresult;
 use style::gecko_bindings::sugar::ownership::{FFIArcHelpers, HasFFI, HasArcFFI, HasBoxFFI};
 use style::gecko_bindings::sugar::ownership::{HasSimpleFFI, Strong};
@@ -162,8 +163,7 @@ fn create_shared_context<'a>(global_style_data: &GlobalStyleData,
         guards: StylesheetGuards::same(guard),
         error_reporter: &DEFAULT_ERROR_REPORTER,
         timer: Timer::new(),
-        // FIXME Find the real QuirksMode information for this document
-        quirks_mode: QuirksMode::NoQuirks,
+        quirks_mode: per_doc_data.stylist.quirks_mode(),
         traversal_flags: traversal_flags,
         snapshot_map: snapshot_map,
     }
@@ -1192,13 +1192,14 @@ pub extern "C" fn Servo_ParseEasing(easing: *const nsAString,
 
 #[no_mangle]
 pub extern "C" fn Servo_ParseStyleAttribute(data: *const nsACString,
-                                            raw_extra_data: *mut URLExtraData)
+                                            raw_extra_data: *mut URLExtraData,
+                                            quirks_mode: nsCompatibility)
                                             -> RawServoDeclarationBlockStrong {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let value = unsafe { data.as_ref().unwrap().as_str_unchecked() };
     let url_data = unsafe { RefPtr::from_ptr_ref(&raw_extra_data) };
     Arc::new(global_style_data.shared_lock.wrap(
-        GeckoElement::parse_style_attribute(value, url_data))).into_strong()
+        GeckoElement::parse_style_attribute(value, url_data, quirks_mode.into()))).into_strong()
 }
 
 #[no_mangle]
@@ -2071,7 +2072,7 @@ pub extern "C" fn Servo_GetComputedKeyframeValues(keyframes: RawGeckoKeyframeLis
         font_metrics_provider: &metrics,
         cached_system_font: None,
         in_media_query: false,
-        quirks_mode: QuirksMode::NoQuirks,
+        quirks_mode: data.stylist.quirks_mode(),
     };
 
     for (index, keyframe) in keyframes.iter().enumerate() {