diff --git a/Cargo.lock b/Cargo.lock
index 67e5cd38f21..194148cc721 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2695,6 +2695,7 @@ dependencies = [
  "msg 0.0.1",
  "script 0.0.1",
  "servo_url 0.0.1",
+ "style 0.0.1",
 ]
 
 [[package]]
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 7c2255d6696..1fea05fc0d9 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use app_units::{Au, AU_PER_PX};
+use cssparser::{Parser, ParserInput};
 use document_loader::{LoadType, LoadBlocker};
 use dom::activation::Activatable;
 use dom::attr::Attr;
@@ -52,10 +53,17 @@ use script_thread::ScriptThread;
 use servo_url::ServoUrl;
 use servo_url::origin::ImmutableOrigin;
 use std::cell::{Cell, RefMut};
+use std::char;
 use std::default::Default;
 use std::i32;
 use std::sync::{Arc, Mutex};
 use style::attr::{AttrValue, LengthOrPercentageOrAuto};
+use style::context::QuirksMode;
+use style::media_queries::MediaQuery;
+use style::parser::ParserContext;
+use style::values::specified::{Length, ViewportPercentageLength};
+use style::values::specified::length::NoCalcLength;
+use style_traits::ParsingMode;
 use task_source::TaskSource;
 
 #[derive(Clone, Copy, HeapSizeOf, JSTraceable)]
@@ -66,6 +74,13 @@ enum State {
     CompletelyAvailable,
     Broken,
 }
+
+#[derive(Debug, PartialEq)]
+pub struct Size {
+    pub query: Option<MediaQuery>,
+    pub length: Length,
+}
+
 #[derive(Clone, Copy, HeapSizeOf, JSTraceable)]
 enum ImageRequestPhase {
     Pending,
@@ -728,6 +743,60 @@ impl LayoutHTMLImageElementHelpers for LayoutDom<HTMLImageElement> {
     }
 }
 
+//https://html.spec.whatwg.org/multipage/#parse-a-sizes-attribute
+pub fn parse_a_sizes_attribute(input: DOMString, width: Option<u32>) -> Vec<Size> {
+    let mut sizes = Vec::<Size>::new();
+    for unparsed_size in input.split(',') {
+        let whitespace = unparsed_size.chars().rev().take_while(|c| char::is_whitespace(*c)).count();
+        let trimmed: String = unparsed_size.chars().take(unparsed_size.chars().count() - whitespace).collect();
+
+        if trimmed.is_empty() {
+            continue;
+        }
+        let mut input = ParserInput::new(&trimmed);
+        let url = ServoUrl::parse("about:blank").unwrap();
+        let context = ParserContext::new_for_cssom(&url,
+                                                   None,
+                                                   ParsingMode::empty(),
+                                                   QuirksMode::NoQuirks);
+        let mut parser = Parser::new(&mut input);
+        let length = parser.try(|i| Length::parse_non_negative(&context, i));
+        match length {
+            Ok(len) => sizes.push(Size {
+                length: len,
+                query: None
+            }),
+            Err(_) => {
+                let mut media_query_parser = parser;
+                let media_query = media_query_parser.try(|i| MediaQuery::parse(&context, i));
+                if let Ok(query) = media_query {
+                    let length = Length::parse_non_negative(&context, &mut media_query_parser);
+                        if let Ok(length) = length {
+                            sizes.push(Size {
+                                length: length,
+                                query: Some(query)
+                        })
+                    }
+                }
+            },
+        }
+    }
+    if sizes.is_empty() {
+        let size = match width {
+            Some(w) => Size {
+                length: Length::from_px(w as f32),
+                query: None
+            },
+            None => Size {
+                length: Length::NoCalc(NoCalcLength::ViewportPercentage(ViewportPercentageLength::Vw(100.))),
+                query: None
+            },
+        };
+        sizes.push(size);
+    }
+    sizes
+}
+
 impl HTMLImageElementMethods for HTMLImageElement {
     // https://html.spec.whatwg.org/multipage/#dom-img-alt
     make_getter!(Alt, "alt");
diff --git a/components/script/test.rs b/components/script/test.rs
index 0ff6811b14d..88baa21f42f 100644
--- a/components/script/test.rs
+++ b/components/script/test.rs
@@ -15,6 +15,10 @@ pub mod area {
     pub use dom::htmlareaelement::{Area, Shape};
 }
 
+pub mod sizes {
+    pub use dom::htmlimageelement::{parse_a_sizes_attribute, Size};
+}
+
 pub mod size_of {
     use dom::characterdata::CharacterData;
     use dom::element::Element;
diff --git a/components/style/servo/media_queries.rs b/components/style/servo/media_queries.rs
index 36e64ee47da..8d99b8ba81e 100644
--- a/components/style/servo/media_queries.rs
+++ b/components/style/servo/media_queries.rs
@@ -164,7 +164,7 @@ pub enum ExpressionKind {
 /// http://dev.w3.org/csswg/mediaqueries-3/#media1
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-pub struct Expression(ExpressionKind);
+pub struct Expression(pub ExpressionKind);
 
 impl Expression {
     /// The kind of expression we're, just for unit testing.
diff --git a/tests/unit/script/Cargo.toml b/tests/unit/script/Cargo.toml
index d88f4d9a75f..7785cced6a9 100644
--- a/tests/unit/script/Cargo.toml
+++ b/tests/unit/script/Cargo.toml
@@ -14,3 +14,4 @@ euclid = "0.15"
 msg = {path = "../../../components/msg"}
 script = {path = "../../../components/script"}
 servo_url = {path = "../../../components/url"}
+style = {path = "../../../components/style"}
diff --git a/tests/unit/script/htmlimageelement.rs b/tests/unit/script/htmlimageelement.rs
new file mode 100644
index 00000000000..5c9106b6c0f
--- /dev/null
+++ b/tests/unit/script/htmlimageelement.rs
@@ -0,0 +1,101 @@
+/* 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/. */
+
+use script::test::DOMString;
+use script::test::sizes::{parse_a_sizes_attribute, Size};
+use style::media_queries::{MediaQuery, MediaQueryType};
+use style::media_queries::Expression;
+use style::servo::media_queries::{ExpressionKind, Range};
+use style::values::specified::{Length, NoCalcLength, AbsoluteLength, ViewportPercentageLength};
+
+pub fn test_length_for_no_default_provided(len: f32) -> Length {
+    let length = Length::NoCalc(NoCalcLength::ViewportPercentage(ViewportPercentageLength::Vw(len)));
+    return length;
+}
+
+#[test]
+fn no_default_provided() {
+    let mut a = vec![];
+    let length = test_length_for_no_default_provided(100f32);
+    let size = Size { query: None, length: length };
+    a.push(size);
+    assert_eq!(parse_a_sizes_attribute(DOMString::new(), None), a);
+}
+
+pub fn test_length_for_default_provided(len: f32) -> Length {
+    let length = Length::NoCalc(NoCalcLength::Absolute(AbsoluteLength::Px(len)));
+    return length;
+}
+
+#[test]
+fn default_provided() {
+    let mut a = vec![];
+    let length = test_length_for_default_provided(2f32);
+    let size = Size { query: None, length: length };
+    a.push(size);
+    assert_eq!(parse_a_sizes_attribute(DOMString::new(), Some(2)), a);
+}
+
+pub fn test_media_query(len: f32) -> MediaQuery {
+    let length = Length::NoCalc(NoCalcLength::Absolute(AbsoluteLength::Px(len)));
+    let expr = Expression(ExpressionKind::Width(Range::Max(length)));
+    let media_query = MediaQuery {
+        qualifier: None,
+        media_type: MediaQueryType::All,
+        expressions: vec![expr]
+    };
+    media_query
+}
+
+pub fn test_length(len: f32) -> Length {
+    let length = Length::NoCalc(NoCalcLength::Absolute(AbsoluteLength::Px(len)));
+    return length;
+}
+
+#[test]
+fn one_value() {
+    let mut a = vec![];
+    let media_query = test_media_query(200f32);
+    let length = test_length(545f32);
+    let size = Size { query: Some(media_query), length: length };
+    a.push(size);
+    assert_eq!(parse_a_sizes_attribute(DOMString::from("(max-width: 200px) 545px"), None), a);
+}
+
+#[test]
+fn more_then_one_value() {
+    let media_query = test_media_query(900f32);
+    let length = test_length(1000f32);
+    let size = Size { query: Some(media_query), length: length };
+    let media_query1 = test_media_query(900f32);
+    let length1 = test_length(50f32);
+    let size1 = Size { query: Some(media_query1), length: length1 };
+    let a = &[size, size1];
+    assert_eq!(parse_a_sizes_attribute(DOMString::from("(max-width: 900px) 1000px, (max-width: 900px) 50px"),
+                None), a);
+}
+
+#[test]
+fn no_extra_whitespace() {
+    let mut a = vec![];
+    let media_query = test_media_query(200f32);
+    let length = test_length(545f32);
+    let size = Size { query: Some(media_query), length: length };
+    a.push(size);
+    assert_eq!(parse_a_sizes_attribute(DOMString::from("(max-width: 200px) 545px"), None), a);
+}
+
+#[test]
+fn extra_whitespace() {
+    let media_query = test_media_query(900f32);
+    let length = test_length(1000f32);
+    let size = Size { query: Some(media_query), length: length };
+    let media_query1 = test_media_query(900f32);
+    let length1 = test_length(50f32);
+    let size1 = Size { query: Some(media_query1), length: length1 };
+    let a = &[size, size1];
+    assert_eq!(parse_a_sizes_attribute(
+        DOMString::from("(max-width: 900px) 1000px,   (max-width: 900px) 50px"),
+        None), a);
+}
diff --git a/tests/unit/script/lib.rs b/tests/unit/script/lib.rs
index 83131e51dd2..21b89a304c5 100644
--- a/tests/unit/script/lib.rs
+++ b/tests/unit/script/lib.rs
@@ -6,10 +6,12 @@ extern crate euclid;
 extern crate msg;
 extern crate script;
 extern crate servo_url;
+extern crate style;
 
 #[cfg(test)] mod origin;
 #[cfg(all(test, target_pointer_width = "64"))] mod size_of;
 #[cfg(test)] mod textinput;
 #[cfg(test)] mod headers;
 #[cfg(test)] mod htmlareaelement;
+#[cfg(test)] mod htmlimageelement;