diff --git a/manuscript/markdown/mainmatter/1.objects/4.composition-and-extension.md b/manuscript/markdown/mainmatter/1.objects/4.composition-and-extension.md
index d88c88c..a994b7c 100644
--- a/manuscript/markdown/mainmatter/1.objects/4.composition-and-extension.md
+++ b/manuscript/markdown/mainmatter/1.objects/4.composition-and-extension.md
@@ -86,7 +86,7 @@ Consider a [queue]:
         pullHead: function () {
           var value;
 
-          if tail >= head {
+          if (tail >= head) {
             value = array[head];
             array[head] = void 0;
             head += 1;
@@ -171,4 +171,4 @@ Now we can extend a queue into a deque:
 
 Presto, we have reuse through extension, at the cost of encapsulation.
 
-T> Encapsulation and Extension exist in a natural state of tension. A program with elaborate encapsulation resists breakage but can also be difficult to refactor in other ways. Be mindful of when it's best to Compose and when it's best to Extend.
\ No newline at end of file
+T> Encapsulation and Extension exist in a natural state of tension. A program with elaborate encapsulation resists breakage but can also be difficult to refactor in other ways. Be mindful of when it's best to Compose and when it's best to Extend.