diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index 29102690a4d..266adea743b 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -997,7 +997,7 @@ impl fmt::Debug for BaseFlow {
 
 impl Encodable for BaseFlow {
     fn encode<S: Encoder>(&self, e: &mut S) -> Result<(), S::Error> {
-        e.emit_struct("base", 0, |e| {
+        e.emit_struct("base", 5, |e| {
             try!(e.emit_struct_field("id", 0, |e| self.debug_id().encode(e)));
             try!(e.emit_struct_field("stacking_relative_position",
                                      1,
@@ -1010,7 +1010,7 @@ impl Encodable for BaseFlow {
                 e.emit_seq(self.children.len(), |e| {
                     for (i, c) in self.children.iter().enumerate() {
                         try!(e.emit_seq_elt(i, |e| {
-                            try!(e.emit_struct("flow", 0, |e| {
+                            try!(e.emit_struct("flow", 2, |e| {
                                 try!(e.emit_struct_field("class", 0, |e| c.class().encode(e)));
                                 e.emit_struct_field("data", 1, |e| {
                                     match c.class() {
diff --git a/components/layout/fragment.rs b/components/layout/fragment.rs
index bfef94fdd0d..967093e2630 100644
--- a/components/layout/fragment.rs
+++ b/components/layout/fragment.rs
@@ -132,7 +132,7 @@ pub struct Fragment {
 
 impl Encodable for Fragment {
     fn encode<S: Encoder>(&self, e: &mut S) -> Result<(), S::Error> {
-        e.emit_struct("fragment", 0, |e| {
+        e.emit_struct("fragment", 3, |e| {
             try!(e.emit_struct_field("id", 0, |e| self.debug_id.encode(e)));
             try!(e.emit_struct_field("border_box", 1, |e| self.border_box.encode(e)));
             e.emit_struct_field("margin", 2, |e| self.margin.encode(e))