diff --git a/doc/differences.md b/doc/differences.md
index 73f5babd0c..7a6189a84c 100644
--- a/doc/differences.md
+++ b/doc/differences.md
@@ -51,7 +51,11 @@ As you can tell, it's not very pretty, unreadable even. Instead of mapping
 directly to a runtime, like other transpilers, 6to5 maps directly to the
 equivalent ES5.
 
-Sometimes there are little things that 6to5 needs
+Sometimes there are little inline functions that 6to5 needs. These are
+placed at the top of your file much like coffee-script does. If these
+are bother you then you can use the [optional runtime](optional-runtime.md).
+We promise that these inline functions will never be significant and will
+always be used as little as possible.
 
 ## Comparison to other transpilers