diff --git a/components/style/properties/longhand/box.mako.rs b/components/style/properties/longhand/box.mako.rs
index a88db8bf03e..69ad8440148 100644
--- a/components/style/properties/longhand/box.mako.rs
+++ b/components/style/properties/longhand/box.mako.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 <%namespace name="helpers" file="/helpers.mako.rs" />
-<% from data import Method, to_rust_ident %>
+<% from data import Keyword, Method, to_rust_ident %>
 
 <% data.new_style_struct("Box",
                          inherited=False,
@@ -126,8 +126,12 @@ ${helpers.single_keyword("clear", "none left right both", gecko_ffi_name="mBreak
   use cssparser::ToCss;
   use std::fmt;
 
-  <% vertical_align_keywords = (
-      "baseline sub super top text-top middle bottom text-bottom".split()) %>
+  <% vertical_align = data.longhands_by_name["vertical-align"] %>
+  <% vertical_align.keyword = Keyword("vertical-align",
+                                      "baseline sub super top text-top middle bottom text-bottom",
+                                      extra_gecko_values="middle-with-baseline") %>
+  <% vertical_align_keywords = vertical_align.keyword.values_for(product) %>
+
   #[allow(non_camel_case_types)]
   #[derive(Debug, Clone, PartialEq, Copy, HeapSizeOf)]
   pub enum SpecifiedValue {
diff --git a/ports/geckolib/properties.mako.rs b/ports/geckolib/properties.mako.rs
index 5ef6f45d568..904181b264d 100644
--- a/ports/geckolib/properties.mako.rs
+++ b/ports/geckolib/properties.mako.rs
@@ -29,7 +29,8 @@ use style::properties::{CascadePropertyFn, ServoComputedValues, ComputedValues};
 use style::properties::longhands;
 use style::properties::make_cascade_vec;
 use style::properties::style_struct_traits::*;
-use values::{ToGeckoStyleCoord, convert_rgba_to_nscolor, convert_nscolor_to_rgba};
+use values::{StyleCoordHelpers, ToGeckoStyleCoord, convert_nscolor_to_rgba};
+use values::{convert_rgba_to_nscolor, debug_assert_unit_is_safe_to_copy};
 use values::round_border_to_device_pixels;
 
 #[derive(Clone)]
@@ -285,9 +286,7 @@ def set_gecko_property(ffi_name, expr):
                                &mut self.gecko.${union_ffi_name});
     }
     fn copy_${ident}_from(&mut self, other: &Self) {
-        use gecko_bindings::structs::nsStyleUnit::eStyleUnit_Calc;
-        debug_assert!(self.gecko.${unit_ffi_name} != eStyleUnit_Calc,
-                      "stylo: Can't yet handle refcounted Calc");
+        debug_assert_unit_is_safe_to_copy(self.gecko.${unit_ffi_name});
         self.gecko.${unit_ffi_name} =  other.gecko.${unit_ffi_name};
         self.gecko.${union_ffi_name} = other.gecko.${union_ffi_name};
     }
@@ -305,10 +304,8 @@ def set_gecko_property(ffi_name, expr):
                                         &mut self.gecko.${y_union_ffi_name});
     }
     fn copy_${ident}_from(&mut self, other: &Self) {
-        use gecko_bindings::structs::nsStyleUnit::eStyleUnit_Calc;
-        debug_assert!(self.gecko.${x_unit_ffi_name} != eStyleUnit_Calc &&
-                      self.gecko.${y_unit_ffi_name} != eStyleUnit_Calc,
-                      "stylo: Can't yet handle refcounted Calc");
+        debug_assert_unit_is_safe_to_copy(self.gecko.${x_unit_ffi_name});
+        debug_assert_unit_is_safe_to_copy(self.gecko.${y_unit_ffi_name});
         self.gecko.${x_unit_ffi_name} = other.gecko.${x_unit_ffi_name};
         self.gecko.${x_union_ffi_name} = other.gecko.${x_union_ffi_name};
         self.gecko.${y_unit_ffi_name} = other.gecko.${y_unit_ffi_name};
@@ -552,20 +549,14 @@ fn static_assert() {
     % endfor
 
     fn set_z_index(&mut self, v: longhands::z_index::computed_value::T) {
-        use gecko_bindings::structs::nsStyleUnit;
         use style::properties::longhands::z_index::computed_value::T;
         match v {
-            T::Auto => {
-                self.gecko.mZIndex.mUnit = nsStyleUnit::eStyleUnit_Auto;
-                unsafe { *self.gecko.mZIndex.mValue.mInt.as_mut() = 0; }
-            }
-            T::Number(n) => {
-                self.gecko.mZIndex.mUnit = nsStyleUnit::eStyleUnit_Integer;
-                unsafe { *self.gecko.mZIndex.mValue.mInt.as_mut() = n; }
-            }
+            T::Auto => self.gecko.mZIndex.set_auto(),
+            T::Number(n) => self.gecko.mZIndex.set_int(n),
         }
     }
     fn copy_z_index_from(&mut self, other: &Self) {
+        debug_assert_unit_is_safe_to_copy(self.gecko.mZIndex.mUnit);
         self.gecko.mZIndex.mUnit = other.gecko.mZIndex.mUnit;
         self.gecko.mZIndex.mValue = other.gecko.mZIndex.mValue;
     }
@@ -632,7 +623,7 @@ fn static_assert() {
 
 </%self:impl_trait>
 
-<%self:impl_trait style_struct_name="Box" skip_longhands="display overflow-y">
+<%self:impl_trait style_struct_name="Box" skip_longhands="display overflow-y vertical-align">
 
     // We manually-implement the |display| property until we get general
     // infrastructure for preffing certain values.
@@ -666,6 +657,24 @@ fn static_assert() {
         }
     }
 
+    fn set_vertical_align(&mut self, v: longhands::vertical_align::computed_value::T) {
+        <% keyword = data.longhands_by_name["vertical-align"].keyword %>
+        use style::properties::longhands::vertical_align::computed_value::T;
+        // FIXME: Align binary representations and ditch |match| for cast + static_asserts
+        match v {
+            % for value in keyword.values_for('gecko'):
+                T::${to_rust_ident(value)} =>
+                    self.gecko.mVerticalAlign.set_int(structs::${keyword.gecko_constant(value)} as i32),
+            % endfor
+            T::LengthOrPercentage(v) => self.gecko.mVerticalAlign.set(v),
+        }
+    }
+    fn copy_vertical_align_from(&mut self, other: &Self) {
+        debug_assert_unit_is_safe_to_copy(self.gecko.mVerticalAlign.mUnit);
+        self.gecko.mVerticalAlign.mUnit = other.gecko.mVerticalAlign.mUnit;
+        self.gecko.mVerticalAlign.mValue = other.gecko.mVerticalAlign.mValue;
+    }
+
 </%self:impl_trait>
 
 <%self:impl_trait style_struct_name="Background" skip_longhands="background-color" skip_additionals="*">
diff --git a/ports/geckolib/values.rs b/ports/geckolib/values.rs
index 069fb9bc9b6..7a313315f1f 100644
--- a/ports/geckolib/values.rs
+++ b/ports/geckolib/values.rs
@@ -4,10 +4,44 @@
 
 use app_units::Au;
 use cssparser::RGBA;
-use gecko_bindings::structs::{nsStyleUnion, nsStyleUnit};
+use gecko_bindings::structs::{nsStyleCoord, nsStyleUnion, nsStyleUnit};
 use std::cmp::max;
 use style::values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto, LengthOrPercentageOrNone};
 
+pub trait StyleCoordHelpers {
+    fn set<T: ToGeckoStyleCoord>(&mut self, val: T);
+    fn set_auto(&mut self);
+    fn set_coord(&mut self, val: Au);
+    fn set_int(&mut self, val: i32);
+    fn set_percent(&mut self, val: f32);
+}
+
+impl StyleCoordHelpers for nsStyleCoord {
+    fn set<T: ToGeckoStyleCoord>(&mut self, val: T) {
+        val.to_gecko_style_coord(&mut self.mUnit, &mut self.mValue);
+    }
+
+    fn set_auto(&mut self) {
+        self.mUnit = nsStyleUnit::eStyleUnit_Auto;
+        unsafe { *self.mValue.mInt.as_mut() = 0; }
+    }
+
+    fn set_coord(&mut self, val: Au) {
+        self.mUnit = nsStyleUnit::eStyleUnit_Coord;
+        unsafe { *self.mValue.mInt.as_mut() = val.0; }
+    }
+
+    fn set_percent(&mut self, val: f32) {
+        self.mUnit = nsStyleUnit::eStyleUnit_Percent;
+        unsafe { *self.mValue.mFloat.as_mut() = val; }
+    }
+
+    fn set_int(&mut self, val: i32) {
+        self.mUnit = nsStyleUnit::eStyleUnit_Integer;
+        unsafe { *self.mValue.mInt.as_mut() = val; }
+    }
+}
+
 pub trait ToGeckoStyleCoord {
     fn to_gecko_style_coord(&self, unit: &mut nsStyleUnit, union: &mut nsStyleUnion);
 }
@@ -95,3 +129,7 @@ pub fn round_border_to_device_pixels(width: Au, au_per_device_px: Au) -> Au {
         max(au_per_device_px, Au(width.0 / au_per_device_px.0 * au_per_device_px.0))
     }
 }
+
+pub fn debug_assert_unit_is_safe_to_copy(unit: nsStyleUnit) {
+    debug_assert!(unit != nsStyleUnit::eStyleUnit_Calc, "stylo: Can't yet handle refcounted Calc");
+}