diff --git a/slime.el b/slime.el
index 5d4d245..7cb0f8f 100644
--- a/slime.el
+++ b/slime.el
@@ -195,6 +195,37 @@ The default is nil, as this feature can be a security risk."
   :type 'integer
   :group 'slime-lisp)
 
+(defvar slime-net-valid-coding-systems
+  '((iso-latin-1-unix nil "iso-latin-1-unix")
+    (iso-8859-1-unix  nil "iso-latin-1-unix")
+    (binary           nil "iso-latin-1-unix")
+    (utf-8-unix       t   "utf-8-unix")
+    (emacs-mule-unix  t   "emacs-mule-unix")
+    (euc-jp-unix      t   "euc-jp-unix"))
+  "A list of valid coding systems. 
+Each element is of the form: (NAME MULTIBYTEP CL-NAME)")
+
+(defun slime-find-coding-system (name)
+  "Return the coding system for the symbol NAME.
+The result is either an element in `slime-net-valid-coding-systems'
+of nil."
+  (let ((probe (assq name slime-net-valid-coding-systems)))
+    (when (and probe (if (fboundp 'check-coding-system)
+                         (ignore-errors (check-coding-system (car probe)))
+                         (eq (car probe) 'binary)))
+      probe)))
+
+(defcustom slime-net-coding-system
+  (car (find-if 'slime-find-coding-system
+                slime-net-valid-coding-systems :key 'car))
+  "Coding system used for network connections.
+See also `slime-net-valid-coding-systems'."
+  :type (cons 'choice
+              (mapcar (lambda (x)
+                        (list 'const (car x)))
+                      slime-net-valid-coding-systems))
+  :group 'slime-lisp)
+
 ;;;;; slime-mode
 
 (defgroup slime-mode nil
@@ -1170,7 +1201,6 @@ Here's an example:
 See `slime-lisp-implementations'")
 
 ;; dummy definitions for the compiler
-(defvar slime-net-coding-system)
 (defvar slime-net-processes)
 (defvar slime-default-connection)
 
@@ -1615,31 +1645,7 @@ line of the file."
 
 ;;;;; Coding system madness
 
-(defvar slime-net-valid-coding-systems
-  '((iso-latin-1-unix nil "iso-latin-1-unix")
-    (iso-8859-1-unix  nil "iso-latin-1-unix")
-    (binary           nil "iso-latin-1-unix")
-    (utf-8-unix       t   "utf-8-unix")
-    (emacs-mule-unix  t   "emacs-mule-unix")
-    (euc-jp-unix      t   "euc-jp-unix"))
-  "A list of valid coding systems. 
-Each element is of the form: (NAME MULTIBYTEP CL-NAME)")
 
-(defun slime-find-coding-system (name)
-  "Return the coding system for the symbol NAME.
-The result is either an element in `slime-net-valid-coding-systems'
-of nil."
-  (let* ((probe (assq name slime-net-valid-coding-systems)))
-    (if (and probe (if (fboundp 'check-coding-system)
-                       (ignore-errors (check-coding-system (car probe)))
-                     (eq (car probe) 'binary)))
-        probe)))
-
-(defvar slime-net-coding-system
-  (find-if 'slime-find-coding-system 
-           '(iso-latin-1-unix iso-8859-1-unix binary))
-  "*Coding system used for network connections.
-See also `slime-net-valid-coding-systems'.")
   
 (defun slime-check-coding-system (coding-system)
   "Signal an error if CODING-SYSTEM isn't a valid coding system."