diff --git a/src/components/main/layout/block.rs b/src/components/main/layout/block.rs
index 73b4f1a7c7e..6057a7a20bf 100644
--- a/src/components/main/layout/block.rs
+++ b/src/components/main/layout/block.rs
@@ -134,8 +134,8 @@ impl BlockFlowData {
         let (left_margin, right_margin) = match width{
             Auto => (left_margin, right_margin),
             Specified(width) => {
-                let left = left_margin.spec_or_default(Au(0));
-                let right = right_margin.spec_or_default(Au(0));
+                let left = left_margin.specified_or_zero();
+                let right = right_margin.specified_or_zero();
                 
                 if((left + right + width) > available_width) {
                     (Specified(left), Specified(right))
@@ -203,10 +203,10 @@ impl BlockFlowData {
                 // Top and bottom margins for blocks are 0 if auto.
                 let margin_top = MaybeAuto::from_margin(style.margin_top(),
                                                         remaining_width,
-                                                        style.font_size()).spec_or_default(Au(0));
+                                                        style.font_size()).specified_or_zero();
                 let margin_bottom = MaybeAuto::from_margin(style.margin_bottom(),
                                                            remaining_width,
-                                                           style.font_size()).spec_or_default(Au(0));
+                                                           style.font_size()).specified_or_zero();
 
                 let (width, margin_left, margin_right) =
                     (MaybeAuto::from_width(style.width(), remaining_width, style.font_size()),
@@ -300,7 +300,7 @@ impl BlockFlowData {
         for self.box.iter().advance |&box| {
             let style = box.style();
             let maybe_height = MaybeAuto::from_height(style.height(), Au(0), style.font_size());
-            let maybe_height = maybe_height.spec_or_default(Au(0));
+            let maybe_height = maybe_height.specified_or_zero();
             height = geometry::max(height, maybe_height);
         }
 
diff --git a/src/components/main/layout/box.rs b/src/components/main/layout/box.rs
index 73f0def93f9..eddca30c436 100644
--- a/src/components/main/layout/box.rs
+++ b/src/components/main/layout/box.rs
@@ -392,13 +392,13 @@ impl RenderBox {
                 let font_size = style.font_size();
                 let w = MaybeAuto::from_width(style.width(),
                                               Au(0),
-                                              font_size).spec_or_default(Au(0));
+                                              font_size).specified_or_zero();
                 let ml = MaybeAuto::from_margin(style.margin_left(),
                                                 Au(0),
-                                                font_size).spec_or_default(Au(0));
+                                                font_size).specified_or_zero();
                 let mr = MaybeAuto::from_margin(style.margin_right(),
                                                 Au(0),
-                                                font_size).spec_or_default(Au(0));
+                                                font_size).specified_or_zero();
                 let pl = base.model.compute_padding_length(style.padding_left(),
                                                            Au(0),
                                                            font_size);
diff --git a/src/components/main/layout/float.rs b/src/components/main/layout/float.rs
index 7f0399eef8e..9681f6e1f64 100644
--- a/src/components/main/layout/float.rs
+++ b/src/components/main/layout/float.rs
@@ -107,16 +107,16 @@ impl FloatFlowData {
                 // Margins for floats are 0 if auto.
                 let margin_top = MaybeAuto::from_margin(style.margin_top(),
                                                         remaining_width,
-                                                        style.font_size()).spec_or_default(Au(0));
+                                                        style.font_size()).specified_or_zero();
                 let margin_bottom = MaybeAuto::from_margin(style.margin_bottom(),
                                                            remaining_width,
-                                                           style.font_size()).spec_or_default(Au(0));
+                                                           style.font_size()).specified_or_zero();
                 let margin_left = MaybeAuto::from_margin(style.margin_left(),
                                                          remaining_width,
-                                                         style.font_size()).spec_or_default(Au(0));
+                                                         style.font_size()).specified_or_zero();
                 let margin_right = MaybeAuto::from_margin(style.margin_right(),
                                                           remaining_width,
-                                                          style.font_size()).spec_or_default(Au(0));
+                                                          style.font_size()).specified_or_zero();
 
 
 
@@ -127,7 +127,7 @@ impl FloatFlowData {
 
                 let width = MaybeAuto::from_width(style.width(), 
                                                   remaining_width,
-                                                  style.font_size()).spec_or_default(shrink_to_fit);
+                                                  style.font_size()).specified_or_default(shrink_to_fit);
                 debug!("assign_widths_float -- width: %?", width);
 
                 model.margin.top = margin_top;
@@ -205,7 +205,7 @@ impl FloatFlowData {
             let height_prop = 
                 MaybeAuto::from_height(box.style().height(),
                                        Au(0),
-                                       box.style().font_size()).spec_or_default(Au(0));
+                                       box.style().font_size()).specified_or_zero();
 
             height = geometry::max(height, height_prop) + noncontent_height;
             debug!("assign_height_float -- height: %?", height);
diff --git a/src/components/main/layout/model.rs b/src/components/main/layout/model.rs
index b3fc4d8d0c1..d7fd674f447 100644
--- a/src/components/main/layout/model.rs
+++ b/src/components/main/layout/model.rs
@@ -80,12 +80,16 @@ impl MaybeAuto {
         }
     }
 
-    pub fn spec_or_default(&self, default: Au) -> Au {
+    pub fn specified_or_default(&self, default: Au) -> Au {
         match *self {
             Auto => default,
             Specified(value) => value,
         }
     }
+
+    pub fn specified_or_zero(&self) -> Au {
+        self.specified_or_default(Au(0))
+    }
 }
 
 impl Zero for BoxModel {