diff --git a/packages/babel/src/traversal/visitors.js b/packages/babel/src/traversal/visitors.js
index 5e60c32976..3545500089 100644
--- a/packages/babel/src/traversal/visitors.js
+++ b/packages/babel/src/traversal/visitors.js
@@ -165,7 +165,7 @@ function ensureEntranceObjects(obj) {
 }
 
 /**
- * [Please add a description.]
+ * Makes sure that enter and exit callbacks are arrays.
  */
 
 function ensureCallbackArrays(obj){