diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 2290825d525..cc89db5e087 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -3149,7 +3149,16 @@ fn static_assert() {
     }
 
     pub fn set_list_style_type(&mut self, v: longhands::list_style_type::computed_value::T) {
-        v.0.to_gecko_value(&mut self.gecko.mCounterStyle);
+        use gecko_bindings::bindings::Gecko_SetCounterStyleToString;
+        use nsstring::{nsACString, nsCString};
+        use self::longhands::list_style_type::computed_value::T;
+        match v {
+            T::CounterStyle(s) => s.to_gecko_value(&mut self.gecko.mCounterStyle),
+            T::String(s) => unsafe {
+                Gecko_SetCounterStyleToString(&mut self.gecko.mCounterStyle,
+                                              &nsCString::from(s) as &nsACString)
+            }
+        }
     }
 
     pub fn copy_list_style_type_from(&mut self, other: &Self) {
diff --git a/components/style/properties/longhand/list.mako.rs b/components/style/properties/longhand/list.mako.rs
index 90d9a9e3f67..7ec59f29e14 100644
--- a/components/style/properties/longhand/list.mako.rs
+++ b/components/style/properties/longhand/list.mako.rs
@@ -31,8 +31,9 @@ ${helpers.single_keyword("list-style-position", "outside inside", animation_valu
         animation_value_type="none",
         spec="https://drafts.csswg.org/css-lists/#propdef-list-style-type")}
 % else:
-    <%helpers:longhand name="list-style-type" animation_value_type="none"
+    <%helpers:longhand name="list-style-type" animation_value_type="none" boxed="True"
                        spec="https://drafts.csswg.org/css-lists/#propdef-list-style-type">
+        use cssparser;
         use std::fmt;
         use style_traits::ToCss;
         use values::CustomIdent;
@@ -44,9 +45,12 @@ ${helpers.single_keyword("list-style-position", "outside inside", animation_valu
         pub mod computed_value {
             use values::generics::CounterStyleOrNone;
 
-            /// <counter-style> | none
+            /// <counter-style> | <string> | none
             #[derive(Debug, Clone, PartialEq, Eq)]
-            pub struct T(pub CounterStyleOrNone);
+            pub enum T {
+                CounterStyle(CounterStyleOrNone),
+                String(String),
+            }
         }
 
         impl ComputedValueAsSpecified for SpecifiedValue {}
@@ -54,7 +58,10 @@ ${helpers.single_keyword("list-style-position", "outside inside", animation_valu
 
         impl ToCss for SpecifiedValue {
             fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-                self.0.to_css(dest)
+                match *self {
+                    SpecifiedValue::CounterStyle(ref s) => s.to_css(dest),
+                    SpecifiedValue::String(ref s) => cssparser::serialize_string(s, dest)
+                }
             }
         }
 
@@ -67,7 +74,7 @@ ${helpers.single_keyword("list-style-position", "outside inside", animation_valu
             /// attribute is considered here.
             pub fn from_gecko_keyword(value: u32) -> Self {
                 use gecko_bindings::structs;
-                SpecifiedValue(if value == structs::NS_STYLE_LIST_STYLE_NONE {
+                SpecifiedValue::CounterStyle(if value == structs::NS_STYLE_LIST_STYLE_NONE {
                     CounterStyleOrNone::None_
                 } else {
                     <%
@@ -86,16 +93,20 @@ ${helpers.single_keyword("list-style-position", "outside inside", animation_valu
 
         #[inline]
         pub fn get_initial_value() -> computed_value::T {
-            computed_value::T(CounterStyleOrNone::disc())
+            computed_value::T::CounterStyle(CounterStyleOrNone::disc())
         }
 
         #[inline]
         pub fn get_initial_specified_value() -> SpecifiedValue {
-            SpecifiedValue(CounterStyleOrNone::disc())
+            SpecifiedValue::CounterStyle(CounterStyleOrNone::disc())
         }
 
         pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
-            CounterStyleOrNone::parse(context, input).map(SpecifiedValue)
+            Ok(if let Ok(style) = input.try(|i| CounterStyleOrNone::parse(context, i)) {
+                SpecifiedValue::CounterStyle(style)
+            } else {
+                SpecifiedValue::String(input.expect_string()?.into_owned())
+            })
         }
     </%helpers:longhand>
 % endif
diff --git a/components/style/properties/shorthand/list.mako.rs b/components/style/properties/shorthand/list.mako.rs
index 2aa0f2a6c82..cb7cc858160 100644
--- a/components/style/properties/shorthand/list.mako.rs
+++ b/components/style/properties/shorthand/list.mako.rs
@@ -61,7 +61,7 @@
             list_style_type::SpecifiedValue::none
             % else:
             use values::generics::CounterStyleOrNone;
-            list_style_type::SpecifiedValue(CounterStyleOrNone::None_)
+            list_style_type::SpecifiedValue::CounterStyle(CounterStyleOrNone::None_)
             % endif
         }
 
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 55bfc2baec8..820c5f43695 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -1844,7 +1844,7 @@ pub extern "C" fn Servo_DeclarationBlock_SetKeywordValue(declarations:
         },
         FontStyle => longhands::font_style::computed_value::T::from_gecko_keyword(value).into(),
         FontWeight => longhands::font_weight::SpecifiedValue::from_gecko_keyword(value),
-        ListStyleType => longhands::list_style_type::SpecifiedValue::from_gecko_keyword(value),
+        ListStyleType => Box::new(longhands::list_style_type::SpecifiedValue::from_gecko_keyword(value)),
         MozMathVariant => longhands::_moz_math_variant::SpecifiedValue::from_gecko_keyword(value),
         WhiteSpace => longhands::white_space::SpecifiedValue::from_gecko_keyword(value),
         CaptionSide => longhands::caption_side::SpecifiedValue::from_gecko_keyword(value),