diff --git a/StreamInterface.php b/StreamInterface.php
index <HASH>..<HASH> 100644
--- a/StreamInterface.php
+++ b/StreamInterface.php
@@ -4,6 +4,9 @@ namespace React\Stream;
 
 use Evenement\EventEmitterInterface;
 
+// This class exists because ReadableStreamInterface and WritableStreamInterface
+//  both need close methods.
+// In PHP <= 5.3.8 a class can not implement 2 interfaces with coincidental matching methods
 interface StreamInterface extends EventEmitterInterface
 {
     public function close();
[Stream]

Documented why new `StreamInterface` exists