diff --git a/components/style/properties/longhand/svg.mako.rs b/components/style/properties/longhand/svg.mako.rs
index 2d0321ad7e0..cc9aadf4e02 100644
--- a/components/style/properties/longhand/svg.mako.rs
+++ b/components/style/properties/longhand/svg.mako.rs
@@ -94,10 +94,9 @@ ${helpers.single_keyword("mask-repeat",
 
 <%helpers:longhand name="mask-position" products="gecko" animatable="True">
     use properties::longhands::background_position;
-    pub mod computed_value {
-        pub type T = ::properties::longhands::background_position::computed_value::T;
-    }
-    pub type SpecifiedValue = background_position::SpecifiedValue;
+    pub use ::properties::longhands::background_position::SpecifiedValue;
+    pub use ::properties::longhands::background_position::single_value as single_value;
+    pub use ::properties::longhands::background_position::computed_value as computed_value;
 
     #[inline]
     pub fn get_initial_value() -> computed_value::T {
@@ -127,10 +126,9 @@ ${helpers.single_keyword("mask-origin",
 
 <%helpers:longhand name="mask-size" products="gecko" animatable="True">
     use properties::longhands::background_size;
-    pub mod computed_value {
-        pub type T = ::properties::longhands::background_size::computed_value::T;
-    }
-    pub type SpecifiedValue = background_size::SpecifiedValue;
+    pub use ::properties::longhands::background_size::SpecifiedValue;
+    pub use ::properties::longhands::background_size::single_value as single_value;
+    pub use ::properties::longhands::background_size::computed_value as computed_value;
 
     #[inline]
     pub fn get_initial_value() -> computed_value::T {
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index e891b051ee3..e55d3d1c06d 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -130,6 +130,7 @@ pub mod shorthands {
     <%include file="/shorthand/inherited_text.mako.rs" />
     <%include file="/shorthand/list.mako.rs" />
     <%include file="/shorthand/margin.mako.rs" />
+    <%include file="/shorthand/mask.mako.rs" />
     <%include file="/shorthand/outline.mako.rs" />
     <%include file="/shorthand/padding.mako.rs" />
     <%include file="/shorthand/position.mako.rs" />
diff --git a/components/style/properties/shorthand/mask.mako.rs b/components/style/properties/shorthand/mask.mako.rs
new file mode 100644
index 00000000000..448dc7ac831
--- /dev/null
+++ b/components/style/properties/shorthand/mask.mako.rs
@@ -0,0 +1,195 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<%helpers:shorthand name="mask" products="gecko"
+                    sub_properties="mask-mode mask-repeat mask-clip mask-origin mask-composite mask-position
+                                    mask-size mask-image">
+    use properties::longhands::{mask_mode, mask_repeat, mask_clip, mask_origin, mask_composite, mask_position};
+    use properties::longhands::{mask_size, mask_image};
+
+    pub fn parse_value(context: &ParserContext, input: &mut Parser) -> Result<Longhands, ()> {
+        % for name in "image mode position size repeat origin clip composite".split():
+            let mut mask_${name} = mask_${name}::SpecifiedValue(Vec::new());
+        % endfor
+
+        try!(input.parse_comma_separated(|input| {
+            % for name in "image mode position size repeat origin clip composite".split():
+                let mut ${name} = None;
+            % endfor
+            loop {
+                if image.is_none() {
+                    if let Ok(value) = input.try(|input| mask_image::single_value
+                                                                   ::parse(context, input)) {
+                        image = Some(value);
+
+                        // Parse mask mode, if applicable.
+                        mode = input.try(|input| mask_mode::single_value::parse(context, input)).ok();
+
+                        continue
+                    }
+                }
+                if position.is_none() {
+                    if let Ok(value) = input.try(|input| mask_position::single_value
+                                                                      ::parse(context, input)) {
+                        position = Some(value);
+
+                        // Parse mask size, if applicable.
+                        size = input.try(|input| {
+                            try!(input.expect_delim('/'));
+                            mask_size::single_value::parse(context, input)
+                        }).ok();
+
+                        continue
+                    }
+                }
+                % for name in "repeat origin clip composite".split():
+                    if ${name}.is_none() {
+                        if let Ok(value) = input.try(|input| mask_${name}::single_value
+                                                                               ::parse(context, input)) {
+                            ${name} = Some(value);
+                            continue
+                        }
+                    }
+                % endfor
+                break
+            }
+            let mut any = false;
+            % for name in "image mode position size repeat origin clip composite".split():
+                any = any || ${name}.is_some();
+            % endfor
+            if any {
+                % for name in "image mode position size repeat origin clip composite".split():
+                    if let Some(m_${name}) = ${name} {
+                        mask_${name}.0.push(m_${name});
+                    } else {
+                        mask_${name}.0.push(mask_${name}::single_value
+                                                        ::get_initial_specified_value());
+                    }
+                % endfor
+                Ok(())
+            } else {
+                Err(())
+            }
+        }));
+
+        Ok(Longhands {
+            % for name in "image mode position size repeat origin clip composite".split():
+                mask_${name}: Some(mask_${name}),
+            % endfor
+         })
+    }
+
+    impl<'a> LonghandsToSerialize<'a>  {
+        fn to_css_declared<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            // mako doesn't like ampersands following `<`
+            fn extract_value<T>(x: &DeclaredValue<T>) -> Option< &T> {
+                match *x {
+                    DeclaredValue::Value(ref val) => Some(val),
+                    _ => None,
+                }
+            }
+            use std::cmp;
+            let mut len = 0;
+            % for name in "image mode position size repeat origin clip composite".split():
+                len = cmp::max(len, extract_value(self.mask_${name}).map(|i| i.0.len())
+                                                                   .unwrap_or(0));
+            % endfor
+
+            // There should be at least one declared value
+            if len == 0 {
+                return dest.write_str("")
+            }
+
+            for i in 0..len {
+                % for name in "image mode position size repeat origin clip composite".split():
+                    let ${name} = if let DeclaredValue::Value(ref arr) = *self.mask_${name} {
+                        arr.0.get(i % arr.0.len())
+                    } else {
+                        None
+                    };
+                % endfor
+
+                if let Some(image) = image {
+                    try!(image.to_css(dest));
+                } else {
+                    try!(write!(dest, "none"));
+                }
+
+                try!(write!(dest, " "));
+
+                if let Some(mode) = mode {
+                    try!(mode.to_css(dest));
+                } else {
+                    try!(write!(dest, "match-source"));
+                }
+
+                try!(write!(dest, " "));
+
+                try!(position.unwrap_or(&mask_position::single_value
+                                                      ::get_initial_specified_value())
+                             .to_css(dest));
+
+                if let Some(size) = size {
+                    try!(write!(dest, " / "));
+                    try!(size.to_css(dest));
+                }
+
+                try!(write!(dest, " "));
+
+                if let Some(repeat) = repeat {
+                    try!(repeat.to_css(dest));
+                } else {
+                    try!(write!(dest, "repeat"));
+                }
+
+                match (origin, clip) {
+                    (Some(origin), Some(clip)) => {
+                        use properties::longhands::mask_origin::single_value::computed_value::T as Origin;
+                        use properties::longhands::mask_clip::single_value::computed_value::T as Clip;
+
+                        try!(write!(dest, " "));
+
+                        match (origin, clip) {
+                            (&Origin::padding_box, &Clip::padding_box) => {
+                                try!(origin.to_css(dest));
+                            },
+                            (&Origin::border_box, &Clip::border_box) => {
+                                try!(origin.to_css(dest));
+                            },
+                            (&Origin::content_box, &Clip::content_box) => {
+                                try!(origin.to_css(dest));
+                            },
+                            _ => {
+                                try!(origin.to_css(dest));
+                                try!(write!(dest, " "));
+                                try!(clip.to_css(dest));
+                            }
+                        }
+                    },
+                    (Some(origin), _) => {
+                        try!(write!(dest, " "));
+                        try!(origin.to_css(dest));
+                    },
+                    (_, Some(clip)) => {
+                        try!(write!(dest, " "));
+                        try!(clip.to_css(dest));
+                    },
+                    _ => {}
+                };
+
+                try!(write!(dest, " "));
+
+                if let Some(composite) = composite {
+                    try!(composite.to_css(dest));
+                } else {
+                    try!(write!(dest, "add"));
+                }
+            }
+
+            Ok(())
+        }
+    }
+</%helpers:shorthand>