diff --git a/ssh-channel.rkt b/ssh-channel.rkt
new file mode 100644
index 0000000..f38d536
--- /dev/null
+++ b/ssh-channel.rkt
@@ -0,0 +1,43 @@
+#lang racket/base
+
+(require racket/set)
+(require racket/match)
+
+(require "ssh-numbers.rkt")
+(require "ssh-message-types.rkt")
+(require "ssh-exceptions.rkt")
+
+(require "os2-support.rkt")
+
+(provide (struct-out ssh-channel))
+
+;; A CloseState is one of
+;; - 'neither, indicating that neither side has signalled closure
+;; - 'local, only the local end has signalled closure
+;; - 'remote, only the remote end has signalled closure
+;; - 'both, both ends have signalled closure.
+;; Represents local knowledge of the state of a shared shutdown state
+;; machine.
+;;
+;;                'neither
+;;                /       \
+;;              \/         \/
+;;           'local      'remote
+;;               \         /
+;;                \/     \/
+;;                  'both
+
+;; A ChannelState is a (ssh-channel ...) TODO
+;; Named ssh-channel to avoid conflicts with Racket's built-in
+;; synchronous channels.
+(struct ssh-channel (my-ref ;; Uint32
+		     your-ref ;; Maybe<Uint32>
+		     type ;; String
+		     continuations ;; TransactionManager (see ordered-rpc.rkt)
+		     outbound-window ;; Maybe<Natural>
+		     outbound-packet-size ;; Maybe<Natural>
+		     inbound-window ;; Natural
+		     eof-state ;; CloseState covering EOF signals
+		     close-state ;; CloseState covering CLOSE signals
+		     )
+	#:transparent)
diff --git a/ssh-session.rkt b/ssh-session.rkt
index 774124f..f884e15 100644
--- a/ssh-session.rkt
+++ b/ssh-session.rkt
@@ -68,37 +68,6 @@
 		    session-id) ;; starts off #f until initial keying
 	#:transparent)
 
-;; A CloseState is one of
-;; - 'neither, indicating that neither side has signalled closure
-;; - 'local, only the local end has signalled closure
-;; - 'remote, only the remote end has signalled closure
-;; - 'both, both ends have signalled closure.
-;; Represents local knowledge of the state of a shared shutdown state
-;; machine.
-;;
-;;                'neither
-;;                /       \
-;;              \/         \/
-;;           'local      'remote
-;;               \         /
-;;                \/     \/
-;;                  'both
-
-;; A ChannelState is a (ssh-channel ...) TODO
-;; Named ssh-channel to avoid conflicts with Racket's built-in
-;; synchronous channels.
-(struct ssh-channel (my-ref ;; Uint32
-		     your-ref ;; Maybe<Uint32>
-		     type ;; String
-		     continuations ;; TransactionManager (see ordered-rpc.rkt)
-		     outbound-window ;; Maybe<Natural>
-		     outbound-packet-size ;; Maybe<Natural>
-		     inbound-window ;; Natural
-		     eof-state ;; CloseState covering EOF signals
-		     close-state ;; CloseState covering CLOSE signals
-		     )
-	#:transparent)
-
 ;; Generic inputs into the exchange-hash part of key
 ;; exchange. Diffie-Hellman uses these fields along with the host key,
 ;; the exchange values, and the shared secret to get the final hash.